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Universal Mathematics Codex & Active Review

Mathematics Codex & Vocabulary Hub

An all-in-one concordance of mathematics. Explore formal definitions, conceptual mechanisms, worked step-by-step procedures, and lesson vocabulary—with interactive formula solvers, 3D active recall flashcards, and audio speech pronunciation.

Interactive Formula Sandbox & Solver

Substitute variables to generate step-by-step mathematical proofs.

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Showing 195 of 195 indexed mathematical concepts & vocabulary terms
A

A — Concepts & Terminology

15 terms

Absolute Value & The Integer Domain

/ˈæbsəluːt ˈvæljuː/ • Latin: "absolutus" (freed, unbound by direction)
Number Systems & Arithmetic Grade 6
Formal Definition & Axiom

The non-negative magnitude of a real number on the continuous number line, representing its geometric distance from origin zero ($0$) irrespective of direction.

Exemplar / Formula
$$|x| = \begin{cases} x & \text{if } x \ge 0 \ -x & \text{if } x < 0 \end{cases}$$
What It Does

It quantifies pure magnitude where direction or sign is irrelevant, such as deviations, financial deficits, depth below sea level, or physical distance.

How To Do It
  • 1 Locate the coordinate $x$ on the real number line.
  • 2 Measure the spatial distance between $x$ and $0$.
  • 3 Drop any negative sign: distance is always non-negative ($|-7| = 7$, $|+7| = 7$).
Worked Exemplum

Problem: Evaluate $|-18| + |12| - |-5|$.

Solution: $|-18| = 18$, $|12| = 12$, and $|-5| = 5$. Compute: $18 + 12 - 5 = 30 - 5 = 25$.

Q.E.D. ∎

Addition Property of Equality

Equations & Inequalities Grade 9
Formal Definition & Axiom

If a = b, then a + c = b + c for any real number c.

Exemplar / Formula
$$\text{If } a = b, \text{ then } a + c = b + c$$

Addition Regrouping & Decomposition (Carrying)

/riːˈɡruːpɪŋ/ • Old French: "groupe" (cluster or bundle)
Number Systems & Arithmetic Grade 2
Formal Definition & Axiom

The algorithmic process of composing a single higher base-ten unit whenever the sum of digits in an existing column equals or exceeds the base value ($10$).

Exemplar / Formula
$$\text{If } O_1 + O_2 \ge 10 \implies \text{Bundle 10 Ones into 1 Ten}$$
What It Does

It preserves place value integrity by ensuring no single digit slot ever exceeds $9$, allowing infinite multi-digit addition.

How To Do It
  • 1 Align addends vertically by column (Hundreds, Tens, Ones).
  • 2 Add the Ones column. If the sum is 10 or greater, record the ones digit below and carry the tens bundle above the next column.
  • 3 Add the Tens column, remembering to include any carried bundle.
Worked Exemplum

Problem: Compute $48 + 37$ with vertical regrouping.

Solution: Ones: $8 + 7 = 15$. Record 5 in ones, carry 1 ten. Tens: $1 \text{ (carried)} + 4 + 3 = 8$. Final sum: $85$.

Q.E.D. ∎

Algebraic Model

Descriptive Statistics Grade 9
Formal Definition & Axiom

A mathematical representation using variables and operations to simulate real-world behaviors and make predictions.

Analyzing a Graph

Descriptive Statistics Grade 9
Formal Definition & Axiom

Core mathematical concept established in Module 5: A Synthesis of Modeling with Equations and Functions, Elements of Modeling.

Analyzing a Verbal Description

Descriptive Statistics Grade 9
Formal Definition & Axiom

Core mathematical concept established in Module 5: A Synthesis of Modeling with Equations and Functions, Elements of Modeling.

Analyzing Data Collected on Two Variables

Descriptive Statistics Grade 9
Formal Definition & Axiom

Core mathematical concept established in Module 2: Descriptive Statistics, Numerical Data on Two Variables.

Area of Rectangles & Polygons

/ˈeəriə/ • Latin: "area" (open space, vacant threshing floor)
Geometry & Measurement Grade 3
Formal Definition & Axiom

The total two-dimensional surface enclosed within a closed boundary, quantified as the aggregate count of square unit tiles ($1 \times 1$) that tile the planar region without overlaps.

Exemplar / Formula
$$A = l \times w = b \times h$$
What It Does

It measures planar coverage: flooring, carpeting, painting walls, solar panel arrays, and farming plots.

How To Do It
  • 1 Measure the perpendicular linear length ($l$) and linear width ($w$) in matching units.
  • 2 Multiply length by width: $A = l \times w$.
  • 3 Attach square units to the product ($\text{in}^2, \text{cm}^2, \text{m}^2$).
Worked Exemplum

Problem: A classroom rug measures $8\text{ ft}$ long and $6\text{ ft}$ wide. Calculate the total floor area covered.

Solution: $A = l \times w = 8 \times 6 = 48\text{ sq ft}$.

Q.E.D. ∎

Arithmetic sequence

Algebraic Foundations & Modeling Grade 9
Formal Definition & Axiom

A sequence is called arithmetic if there is a real number d such that each term in the sequence is the sum of the previous term and d.

Associative Property

Polynomials & Algebraic Expressions Grade 9
Formal Definition & Axiom

The property stating that the grouping of numbers being added or multiplied does not change the result: (a + b) + c = a + (b + c) and (ab)c = a(bc).

Average Rate of Change

Linear & Piecewise Functions Grade 9
Formal Definition & Axiom

The change in the dependent variable (elevation) divided by the change in the independent variable (time) over a given interval. Graphically, this is the slope of the line segment.

Exemplar / Formula
$$\text{Average Rate of Change} = \frac{f(b) - f(a)}{b - a} = \frac{\Delta y}{\Delta x}$$

Axiomatic Triangle Congruence (SSS, SAS, ASA, AAS, HL)

/ˈkɒŋɡruəns/ • Latin: "congruere" (to agree together, correspond exactly)
Geometry & Measurement Grade 10
Formal Definition & Axiom

Geometric postulates establishing that two triangles possess identical size and shape if a specific subset of corresponding sides and angles are proven equal.

Exemplar / Formula
$$\Delta ABC \cong \Delta DEF \iff \text{Rigid Motion Maps } \Delta ABC \to \Delta DEF$$
What It Does

It allows rigorous mathematical proof: once two triangles are proven congruent by 3 pieces of criteria, all 6 corresponding parts are guaranteed congruent (CPCTC).

How To Do It
  • 1 Identify given information and mark congruent side and angle pairs on the diagram.
  • 2 Look for shared sides (Reflexive Property) or vertical angles.
  • 3 Match to a valid congruence criteria (SSS, SAS, ASA, AAS, or Hypotenuse-Leg for right triangles). Never use unproven configurations like SSA or AAA.
Worked Exemplum

Problem: Two triangles share side $AC$. Side $AB \cong AD$ and $\angle BAC \cong \angle DAC$. Prove $\Delta ABC \cong \Delta ADC$.

Solution: $AB \cong AD$ (Side), $\angle BAC \cong \angle DAC$ (Angle), and $AC \cong AC$ (Side via Reflexive Property). Triangles are congruent by $\text{SAS Congruence Postulate}$.

Q.E.D. ∎
B

B — Concepts & Terminology

6 terms

Base Multiplier (b)

Exponential Functions Grade 9
Formal Definition & Axiom

The constant factor by which the function value is multiplied each time $x$ increases by 1 unit. When $b > 1$, the function models growth; when $0 < b < 1$, it models exponential decay.

Exemplar / Formula
$$b = \frac{f(x+1)}{f(x)}$$

Base-Ten Place Value (Tens & Ones)

/beɪs tɛn pleɪs ˈvæljuː/ • Latin: "decimalis" (of tenths)
Number Systems & Arithmetic Grade 1
Formal Definition & Axiom

The value of a digit determined strictly by its position within a number, where each unit in the tens column equals an aggregate group of ten individual single units.

Exemplar / Formula
$$\text{Two-Digit Number} = (T \times 10) + (O \times 1)$$
What It Does

It allows humans to express any quantity using only ten symbols ($0$ through $9$) by bundling groups into bundles of ten, avoiding the need for infinite distinct numeral marks.

How To Do It
  • 1 Count out the total single units into complete bundles of ten.
  • 2 Write the count of complete 10-bundles in the left column (Tens).
  • 3 Write any remaining loose single units in the right column (Ones).
Worked Exemplum

Problem: Decompose the quantity $47$ into its foundational base-ten components.

Solution: 47 contains 4 bundles of ten and 7 loose units: $47 = (4 \times 10) + (7 \times 1) = 40 + 7$.

Q.E.D. ∎

Binomial

/baɪˈnoʊmiəl/ • Latin: "bi" (two) + "nomen" (name/term)
Polynomials & Algebraic Expressions Grade 9, Grade 11
Formal Definition & Axiom

A polynomial with exactly two terms, such as x + 4 or 3x² - 2.

Exemplar / Formula
$$(a + b)^n = \sum_{k=0}^{n} \binom{n}{k} a^{n-k} b^k \quad \left(\binom{n}{k} = \frac{n!}{k!(n-k)!}\right)$$
What It Does

It bypasses manual, error-prone repeated polynomial multiplications (like multiplying $(a+b)$ five times), expanding higher-degree powers in a single structured sweep.

How To Do It
  • 1 Identify row $n$ in Pascal's Triangle to obtain coefficients $\binom{n}{k}$.
  • 2 Write descending powers of $a$ from $a^n$ down to $a^0$.
  • 3 Write ascending powers of $b$ from $b^0$ up to $b^n$.
  • 4 Multiply coefficients and variable powers together for each term.
Worked Exemplum

Problem: Expand $(x + 2)^3$ using the Binomial Theorem.

Solution: Row 3 coefficients: $1, 3, 3, 1$. Expand: $1(x^3)(2^0) + 3(x^2)(2^1) + 3(x^1)(2^2) + 1(x^0)(2^3) = x^3 + 6x^2 + 12x + 8$.

Q.E.D. ∎

Box plots

Algebraic Foundations & Modeling Grade 9
Formal Definition & Axiom

A graph that provides a picture of the data ordered and divided into four intervals that each contains approximately 25% of the data.

C

C — Concepts & Terminology

19 terms

Circle Geometry: Circumference & Area

/səˈkʌmfərəns/ • Greek: "π" (perimetros, circumference)
Geometry & Measurement Grade 7
Formal Definition & Axiom

Geometric relationships for any Euclidean circle, where Circumference ($C$) is the boundary perimeter and Area ($A$) is the internal planar surface, both governed by the transcendental constant $\pi \approx 3.14159$.

Exemplar / Formula
$$C = 2\pi r = \pi d, \quad A = \pi r^2$$
What It Does

It allows precise calculation of round perimeters (wheels, tracks) and circular surface areas (pipes, pizza slices, fields) from a single radial measurement.

How To Do It
  • 1 Identify radius ($r$). If given diameter ($d$), divide by $2$ ($r = d/2$).
  • 2 For perimeter/circumference, compute $C = 2 \times \pi \times r$.
  • 3 For interior surface area, square the radius first ($r^2$), then multiply by $\pi$: $A = \pi \times r^2$.
Worked Exemplum

Problem: A circular trampoline has a radius of $7\text{ ft}$. Calculate its exact circumference and area in terms of $\pi$.

Solution: Circumference: $C = 2\pi(7) = 14\pi\text{ ft}$. Area: $A = \pi(7^2) = 49\pi\text{ sq ft}$.

Q.E.D. ∎

Closed Circle

Equations & Inequalities Grade 9
Formal Definition & Axiom

A solid filled dot on a number line representing an inclusive boundary that is included in the solution set (≤ or ≥).

Closure

Algebraic Foundations & Modeling Grade 9
Formal Definition & Axiom

A set has closure under an operation if performing that operation on members of the set always produces a member of the same set. Polynomials are closed under addition and subtraction.

Combined Rate

Algebraic Foundations & Modeling Grade 9
Formal Definition & Axiom

The total operational output rate achieved when multiple independent agents or machines work concurrently.

Commutative Property

/kəˈmjuːtətɪv/ • Latin: "commutare" (to interchange or swap)
Polynomials & Algebraic Expressions Grade 9, Grade 1
Formal Definition & Axiom

The property stating that the order in which two real numbers are added or multiplied does not change the result: a + b = b + a and ab = ba.

Exemplar / Formula
$$a + b = b + a$$
What It Does

It halves the memory required for mental math fact fluency: if you know $3 + 8 = 11$, you automatically know $8 + 3 = 11$.

How To Do It
  • 1 Identify the two addends being combined.
  • 2 Start with the larger number first to minimize manual counting efforts (Count-On Strategy).
  • 3 Add the smaller addend: the resulting sum is invariant.
Worked Exemplum

Problem: Calculate $2 + 9$ using the Commutative Property.

Solution: Swap addends: $2 + 9 = 9 + 2$. Count on 2 units from 9: $9 \to 10 \to 11$. Sum is $11$.

Q.E.D. ∎

Comparing Distributions

Descriptive Statistics Grade 9
Formal Definition & Axiom

Core mathematical concept established in Module 2: Descriptive Statistics, Calculating and Interpreting Measures of Center and Variability.

Completing the Square

Quadratic Functions & Equations Grade 9
Formal Definition & Axiom

Core mathematical concept established in Module 4: Polynomial and Quadratic Expressions, Equations, and Functions, Using Different Forms for Quadratic Functions.

Complex Numbers & The Imaginary Unit

/ˈkɒm.plɛks/ • Latin: "complexus" (interwoven, composite of real and imaginary)
Algebraic Foundations & Modeling Grade 11
Formal Definition & Axiom

An extension of the one-dimensional real number system into a two-dimensional complex plane ($\mathbb{C}$), defined by the imaginary unit $i$ whose square equals $-1$.

Exemplar / Formula
$$z = a + bi \quad (i = \sqrt{-1}, \; i^2 = -1, \; a, b \in \mathbb{R})$$
What It Does

It eliminates the barrier of negative square roots, guaranteeing that every $n$-th degree polynomial has exactly $n$ complex roots (Fundamental Theorem of Algebra). Powers electrical engineering and quantum physics.

How To Do It
  • 1 Treat $i$ algebraically like a variable, combining real parts with real parts and imaginary parts with imaginary parts: $(a + bi) + (c + di) = (a+c) + (b+d)i$.
  • 2 When multiplying, expand via FOIL and replace any occurrence of $i^2$ with $-1$.
  • 3 To divide, multiply numerator and denominator by the complex conjugate $a - bi$.
Worked Exemplum

Problem: Multiply $(3 + 2i)(1 - 4i)$.

Solution: FOIL: $3(1) + 3(-4i) + 2i(1) + 2i(-4i) = 3 - 12i + 2i - 8i^2$. Replace $i^2 = -1$: $3 - 10i - 8(-1) = 3 - 10i + 8 = 11 - 10i$.

Q.E.D. ∎

Conditional Relative Frequencies and Association

Descriptive Statistics Grade 9
Formal Definition & Axiom

Core mathematical concept established in Module 2: Descriptive Statistics, Categorical Data on Two Variables.

Conjunction ('And')

Algebraic Foundations & Modeling Grade 9
Formal Definition & Axiom

A compound sentence that is true only if both of its component statements are simultaneously true. Corresponding to set intersection (∩).

Creating and Solving Quadratic Equations in One Variable

Quadratic Functions & Equations Grade 9
Formal Definition & Axiom

Core mathematical concept established in Module 4: Polynomial and Quadratic Expressions, Equations, and Functions, Quadratic Expressions, Equations, and Functions.

D

D — Concepts & Terminology

12 terms

Deductive Reasoning

Algebraic Foundations & Modeling Grade 9
Formal Definition & Axiom

A logical process in which a conclusion is based on the concordance of multiple premises that are assumed or proven to be true.

Degree of a Polynomial

Polynomials & Algebraic Expressions Grade 9
Formal Definition & Axiom

The highest exponent of the variable in any term of the polynomial (when in one variable).

Degree Sum Theorem

Algebraic Foundations & Modeling Grade 9
Formal Definition & Axiom

For non-zero polynomials P and Q, deg(P · Q) = deg(P) + deg(Q).

Dependent Variable

Linear & Piecewise Functions Grade 9
Formal Definition & Axiom

The output value of a function, which depends on the input value (usually elevation/height, graphed on the vertical axis).

Derivative via Difference Quotient

/dɪˈrɪvətɪv/ • Latin: "derivare" (to draw off from a source stream)
Calculus & Analysis Grade 12
Formal Definition & Axiom

The instantaneous rate of change of a differentiable continuous function with respect to its independent variable, geometrically representing the exact slope of the tangent line at any point $x$.

Exemplar / Formula
$$f'(x) = \lim_{h \to 0} \frac{f(x + h) - f(x)}{h}$$
What It Does

It freezes continuous motion at a single infinitesimal point in time, revealing exact velocities, rates of biological growth, and market volatility.

How To Do It
  • 1 Substitute $x + h$ into the function $f(x)$ to evaluate $f(x + h)$.
  • 2 Formulate the difference quotient: $\frac{f(x + h) - f(x)}{h}$.
  • 3 Algebraically cancel the factor of $h$ from the denominator.
  • 4 Evaluate the limit by taking $h \to 0$.
Worked Exemplum

Problem: Find the derivative of $f(x) = x^2$ using the limit definition.

Solution: $\lim_{h \to 0} \frac{(x+h)^2 - x^2}{h} = \lim_{h \to 0} \frac{x^2 + 2xh + h^2 - x^2}{h} = \lim_{h \to 0} \frac{2xh + h^2}{h} = \lim_{h \to 0} (2x + h) = 2x$.

Q.E.D. ∎

Deriving the Quadratic Formula

Quadratic Functions & Equations Grade 9
Formal Definition & Axiom

Core mathematical concept established in Module 4: Polynomial and Quadratic Expressions, Equations, and Functions, Using Different Forms for Quadratic Functions.

Describing the Center of a Distribution

Descriptive Statistics Grade 9
Formal Definition & Axiom

Core mathematical concept established in Module 2: Descriptive Statistics, Shapes and Centers of Distributions.

Distributive Property

/dɪˈstrɪbjʊtɪv/ • Latin: "distribuere" (to apportion or divide up)
Polynomials & Algebraic Expressions Grade 9, Grade 3
Formal Definition & Axiom

The mathematical axiom asserting that multiplying a sum by a number gives the same result as multiplying each addend separately and adding the products: a(b + c) = ab + ac.

Exemplar / Formula
$$a(b + c) = ab + ac \quad \text{and} \quad (b + c)a = ba + ca$$
What It Does

It allows complex mental arithmetic by breaking intimidating numbers (like $7 \times 14$) into two effortless friendly facts ($7 \times 10 + 7 \times 4$).

How To Do It
  • 1 Break one tough factor into two easier additive parts (e.g., $14 = 10 + 4$).
  • 2 Multiply the outside multiplier by the first decomposed part.
  • 3 Multiply the outside multiplier by the second decomposed part.
  • 4 Add the two partial products together.
Worked Exemplum

Problem: Evaluate $8 \times 13$ using the Distributive Property.

Solution: Decompose $13 = 10 + 3$: $8 \times (10 + 3) = (8 \times 10) + (8 \times 3) = 80 + 24 = 104$.

Q.E.D. ∎

Dot plots

Algebraic Foundations & Modeling Grade 9
Formal Definition & Axiom

A plot of each data value on a scale or number line.

E

E — Concepts & Terminology

16 terms

Effective Tax Rate

Algebraic Foundations & Modeling Grade 9
Formal Definition & Axiom

The actual percentage of total income paid in taxes: (Total Tax Paid / Total Income) * 100%.

Elimination Method

Equations & Inequalities Grade 9
Formal Definition & Axiom

An algebraic technique where equations are added or subtracted to cancel out one of the variables.

End behavior of a graph

Quadratic Functions & Equations Grade 9
Formal Definition & Axiom

Given a quadratic function in the form f(x)=ax^{2}+bx+c (or f(x)=a(x-h)^{2}+k), the quadratic function is said to open up if a>0 and open down if a<0.

Equation

/ˈsɪstəmz/ • Greek: "systema" (organized whole composition)
Equations & Inequalities Grade 9, Grade 8
Formal Definition & Axiom

A mathematical statement asserting that two algebraic expressions are equal in value.

Exemplar / Formula
$$\begin{cases} a_1 x + b_1 y = c_1 \ a_2 x + b_2 y = c_2 \end{cases} \implies \text{Intersection Point } (x, y)$$
What It Does

It models break-even points in economics, mixing chemical solutions, flight intersection paths, and dual-variable constraints.

How To Do It
  • 1 Multiply one or both equations by a constant so that coefficients of one variable are exact opposites.
  • 2 Add the two equations vertically to eliminate that variable.
  • 3 Solve the resulting single-variable equation.
  • 4 Back-substitute into either original equation to find the other variable.
Worked Exemplum

Problem: Solve the linear system: $2x + y = 7$ and $x - y = 2$.

Solution: Add equations: $(2x + y) + (x - y) = 7 + 2 \implies 3x = 9 \implies x = 3$. Substitute: $3 - y = 2 \implies y = 1$. Solution: $(3, 1)$.

Q.E.D. ∎

Equivalent Expressions

Algebraic Foundations & Modeling Grade 9
Formal Definition & Axiom

Two algebraic expressions that yield the exact same numerical result whenever the same values are substituted for their variables.

Estimating Centers and Interpreting the Mean as a Balance Point

Descriptive Statistics Grade 9
Formal Definition & Axiom

Core mathematical concept established in Module 2: Descriptive Statistics, Shapes and Centers of Distributions.

Euclidean Division Algorithm (Long Division)

/lɔːŋ dɪˈvɪʒən/ • Latin: "divisio" (distribution among shares)
Number Systems & Arithmetic Grade 4
Formal Definition & Axiom

An iterative place-value algorithm that determines how many times a positive integer divisor ($b$) partitions into a dividend ($a$), yielding an integer quotient ($q$) and an exact remainder ($r$).

Exemplar / Formula
$$a = bq + r \quad (0 \le r < b)$$
What It Does

It enables the exact and step-by-step division of arbitrarily large multi-digit numbers by breaking the computation down column-by-column.

How To Do It
  • 1 Divide: Determine how many times the divisor fits into the current active place-value digit(s).
  • 2 Multiply: Multiply the resulting quotient digit by the divisor.
  • 3 Subtract: Subtract that product from the active digits to find the local remainder.
  • 4 Bring Down: Bring down the next digit of the dividend and repeat.
Worked Exemplum

Problem: Divide $496 \div 4$ using the standard long division algorithm.

Solution: $4 \div 4 = 1$ (rem 0). Bring down 9: $9 \div 4 = 2$ ($2 \times 4 = 8$, rem 1). Bring down 6: $16 \div 4 = 4$ ($4 \times 4 = 16$, rem 0). Quotient is $124$.

Q.E.D. ∎

Explicit (Closed-Form) Formula

Algebraic Foundations & Modeling Grade 9
Formal Definition & Axiom

A formula allowing direct calculation of the nth term of a sequence using only the index n, without computing any preceding terms.

Explore the following question

Algebraic Foundations & Modeling Grade 9
Formal Definition & Axiom

How would the relative frequencies look if males and females had the same opinions about their favorite superpowers? This question is a prelude to Lesson 11.

Exponential Decay

Exponential Functions Grade 9
Formal Definition & Axiom

Core mathematical concept established in Module 3: Linear and Exponential Functions, Linear and Exponential Sequences.

Exponential Function

Exponential Functions Grade 9
Formal Definition & Axiom

A function in which an independent variable appears as an exponent: $f(x) = a \cdot b^x$. The rate of change increases directly in proportion to the magnitude of the function value itself.

Exemplar / Formula
$$f(x) = a \cdot b^x \quad (a \ne 0, \, b > 0, \, b \ne 1)$$

Exponential Growth & Decay Models

/ˌɛkspəˈnɛnʃəl/ • Latin: "exponere" (to exhibit, put forth into powers)
Algebraic Foundations & Modeling Grade 9
Formal Definition & Axiom

A non-linear mathematical model where the rate of change is proportional to the current amount, resulting in geometric compounding over continuous or discrete time intervals $t$.

Exemplar / Formula
$$y = a(1 \pm r)^t \quad \left(\text{Growth: } +r, \; \text{Decay: } -r\right)$$
What It Does

It accurately models viral contagion, compound investment interest, population explosions, and radioactive carbon decay.

How To Do It
  • 1 Identify initial amount ($a$) and decimal rate of change ($r$).
  • 2 Construct the growth factor ($1 + r$) or decay factor ($1 - r$).
  • 3 Substitute elapsed time periods ($t$) into the exponent and evaluate.
Worked Exemplum

Problem: A colony of $500$ bacteria doubles ($r = 1.0$) every hour. How many bacteria exist after $4\text{ hours}$?

Solution: $y = a(1 + r)^t = 500(1 + 1)^4 = 500(2^4) = 500(16) = 8,000\text{ bacteria}$.

Q.E.D. ∎

Extraneous Solution

Equations & Inequalities Grade 9
Formal Definition & Axiom

A solution that emerges from the process of solving an equation but is not a valid solution to the original equation.

F

F — Concepts & Terminology

11 terms

Factored Form

Algebraic Foundations & Modeling Grade 9
Formal Definition & Axiom

An expression expressed as a product of irreducible linear or polynomial factors.

Feasible Region

Equations & Inequalities Grade 9
Formal Definition & Axiom

The intersection of all half-planes defined by a system of inequalities representing all viable solutions.

Formula

/kwɒˈdrætɪk/ • Latin: "quadratus" (squared, four-sided square)
Algebraic Foundations & Modeling Grade 9
Formal Definition & Axiom

A mathematical relationship or rule expressed with algebraic symbols (e.g., V = lwh).

Exemplar / Formula
$$x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \quad (\Delta = b^2 - 4ac)$$
What It Does

It solves any parabolic or quadratic equation, even when factoring fails. It models trajectories, projectiles, revenue optimization, and physics mechanics.

How To Do It
  • 1 Set equation into standard form: $ax^2 + bx + c = 0$.
  • 2 Identify coefficients $a, b, c$ with their respective signs.
  • 3 Evaluate the discriminant: $\Delta = b^2 - 4ac$ ($\Delta > 0 \implies 2\text{ real roots}$; $\Delta = 0 \implies 1\text{ root}$; $\Delta < 0 \implies \text{complex roots}$).
  • 4 Compute the two roots via $\pm$ in the numerator.
Worked Exemplum

Problem: Solve $x^2 - 5x + 6 = 0$ using the Quadratic Formula.

Solution: $a=1, b=-5, c=6$. $\Delta = (-5)^2 - 4(1)(6) = 25 - 24 = 1$. $x = \frac{-(-5) \pm \sqrt{1}}{2(1)} = \frac{5 \pm 1}{2} \implies x = 3 \text{ or } x = 2$.

Q.E.D. ∎

FORMULATE AND COMPUTE

Algebraic Foundations & Modeling Grade 9
Formal Definition & Axiom

During this phase of the lesson, students should work in small groups.

For the equation

Equations & Inequalities Grade 9
Formal Definition & Axiom

I first looked for the function type, which narrowed my search considerably.

For the graph

Quadratic Functions & Equations Grade 9
Formal Definition & Axiom

I looked at the overall shape first to identify what type of graph it was (quadratic, linear, exponential, piecewise, square root, or cube root).

Fraction Addition with Unlike Denominators

/ʌnˈlaɪk dɪˈnɒmɪneɪtərz/ • Latin: "denominare" (to name or specify)
Fractions & Rational Numbers Grade 5
Formal Definition & Axiom

The method of renaming fractions into equivalent representations sharing a common unit measure (the Least Common Denominator) prior to combining numerators.

Exemplar / Formula
$$\frac{a}{b} + \frac{c}{d} = \frac{ad + bc}{bd}$$
What It Does

Fractions cannot be added directly if their pieces are different sizes (e.g. halves and thirds); finding the LCD cuts all pieces into identical units so they can be summed.

How To Do It
  • 1 Find the Least Common Multiple (LCM) of denominators $b$ and $d$.
  • 2 Multiply numerator and denominator of each fraction by the factor needed to attain the LCD.
  • 3 Add the newly aligned numerators while keeping the common denominator constant.
  • 4 Simplify to lowest terms if possible.
Worked Exemplum

Problem: Compute $\frac{2}{3} + \frac{1}{4}$.

Solution: $\text{LCM}(3, 4) = 12$. Scale fractions: $\frac{2 \times 4}{3 \times 4} = \frac{8}{12}$, $\frac{1 \times 3}{4 \times 3} = \frac{3}{12}$. Add: $\frac{8 + 3}{12} = \frac{11}{12}$.

Q.E.D. ∎

Fraction Division via Reciprocal (Keep-Change-Flip)

/rɪˈsɪprəkəl/ • Latin: "reciprocus" (moving back and forth, alternating)
Fractions & Rational Numbers Grade 6
Formal Definition & Axiom

An algebraic law establishing that dividing by a rational fraction is mathematically equivalent to multiplying by its multiplicative inverse (reciprocal).

Exemplar / Formula
$$\frac{a}{b} \div \frac{c}{d} = \frac{a}{b} \times \frac{d}{c} = \frac{ad}{bc}$$
What It Does

Division answers "how many groups fit inside." Multiplying by the flipped reciprocal counts how many sub-units fit without laborious manual partitioning.

How To Do It
  • 1 Keep: Leave the dividend (first fraction) unchanged.
  • 2 Change: Invert the division operator ($\div$) into multiplication ($\times$).
  • 3 Flip: Invert the divisor (second fraction) into its reciprocal ($\frac{c}{d} \to \frac{d}{c}$).
  • 4 Multiply straight across and reduce.
Worked Exemplum

Problem: Compute $\frac{3}{4} \div \frac{2}{5}$.

Solution: Keep $\frac{3}{4}$, Change $\div$ to $\times$, Flip $\frac{2}{5} \to \frac{5}{2}$: $\frac{3}{4} \times \frac{5}{2} = \frac{3 \times 5}{4 \times 2} = \frac{15}{8} = 1\frac{7}{8}$.

Q.E.D. ∎

Fundamental Theorem of Calculus (FTC)

/ˌfʌndəˈmɛntl ˈθɪərəm/ • Latin: "fundamentum" (groundwork, base cornerstone)
Calculus & Analysis Grade 12
Formal Definition & Axiom

The unifying theorem of mathematical analysis demonstrating that differentiation and integration are inverse operations: the definite integral (net accumulated area) can be calculated via anti-derivatives.

Exemplar / Formula
$$\int_{a}^{b} f(x) \, dx = F(b) - F(a) \quad \left(\text{where } F'(x) = f(x)\right)$$
What It Does

It bridges geometry (accumulating area under curves) with algebra (reversing derivatives), enabling exact calculation of areas, volumes of revolution, and total physical work.

How To Do It
  • 1 Find the antiderivative function $F(x)$ such that $F'(x) = f(x)$.
  • 2 Evaluate the antiderivative at the upper integration limit ($F(b)$).
  • 3 Evaluate the antiderivative at the lower integration limit ($F(a)$).
  • 4 Subtract: $\text{Net Area} = F(b) - F(a)$.
Worked Exemplum

Problem: Evaluate the definite integral $\int_{0}^{3} 2x \, dx$.

Solution: Antiderivative of $2x$ is $F(x) = x^2$. Evaluate: $F(3) - F(0) = 3^2 - 0^2 = 9 - 0 = 9$.

Q.E.D. ∎
G

G — Concepts & Terminology

7 terms

Geometric Sequence

Algebraic Foundations & Modeling Grade 9
Formal Definition & Axiom

A geometric sequence goes from one term to the next by multiplying (or dividing) by the same value.

Graphing Cubic, Square Root, and Cube Root Functions

Quadratic Functions & Equations Grade 9
Formal Definition & Axiom

Core mathematical concept established in Module 4: Polynomial and Quadratic Expressions, Equations, and Functions, Function Transformations and Modeling.

Graphing Quadratic Functions from Factored Form, f(x)=a(x-m)(x-n)

Quadratic Functions & Equations Grade 9
Formal Definition & Axiom

Core mathematical concept established in Module 4: Polynomial and Quadratic Expressions, Equations, and Functions, Quadratic Expressions, Equations, and Functions.

Graph of an Equation

Equations & Inequalities Grade 9
Formal Definition & Axiom

The set of all points on the coordinate plane whose coordinates (x, y) satisfy the equation.

Graphs Can Solve Equations Too

Exponential Functions Grade 9
Formal Definition & Axiom

Core mathematical concept established in Module 3: Linear and Exponential Functions, Transformations of Functions.

Graphs Example

Algebraic Foundations & Modeling Grade 9
Formal Definition & Axiom

Graphs Data are often summarized by graphs; the graphs are the first indicator of variability in the data.

Greatest Common Factor (GCF) & Euclidean Algorithm

/ˈɡreɪtɪst ˈkɒmən ˈfæktər/ • Greek: "arithmos" (prime numbers)
Number Systems & Arithmetic Grade 6
Formal Definition & Axiom

The largest natural number that evenly divides two or more integers without leaving a remainder, forming the basis of simplifying fractions.

Exemplar / Formula
$$\gcd(a, b) = \gcd(b, a \bmod b) \quad (\gcd(a, 0) = a)$$
What It Does

It finds the maximum bundle size when grouping disparate collections into identical subsets, and reduces fractions to their simplest indivisible terms.

How To Do It
  • 1 Find the prime factorizations of both numbers.
  • 2 Identify all common prime factors shared by both sets.
  • 3 Multiply the shared common prime factors together to obtain the GCF.
Worked Exemplum

Problem: Find the Greatest Common Factor of $24$ and $36$.

Solution: Prime factorization: $24 = 2^3 \times 3$, $36 = 2^2 \times 3^2$. Common prime factors: $2^2 \times 3 = 4 \times 3 = 12$. $\text{GCF} = 12$.

Q.E.D. ∎
H

H — Concepts & Terminology

4 terms

Histograms

Descriptive Statistics Grade 9
Formal Definition & Axiom

A graph of data that groups the data based on intervals and represents the data in each interval by a bar.

Horizontal Asymptote

Exponential Functions Grade 9
Formal Definition & Axiom

A horizontal line ($y = 0$ for basic exponential curves) that the curve approaches closer and closer as $x \to -\infty$, but never intersects or passes.

Exemplar / Formula
$$y = 0 \quad \text{as } x \to -\infty \text{ for } f(x) = 2^x$$
I

I — Concepts & Terminology

14 terms

Identity

Equations & Inequalities Grade 9
Formal Definition & Axiom

An equation that evaluates to True for all possible values of its variables (e.g., 2(x + 1) = 2x + 2).

If f

Algebraic Foundations & Modeling Grade 9
Formal Definition & Axiom

R→R is the function such that x↦x^{2}, then the range of f is the set of all nonnegative real numbers.

If not

Descriptive Statistics Grade 9
Formal Definition & Axiom

Notice that in the next table in your packet (Brand A), the second row says "Deviation from the Mean.

Indefinite Integrals & Antidifferentiation

/ˈɪndɛfɪnɪt ˈɪntɪɡrəl/ • Latin: "integrare" (to make whole, aggregate)
Calculus & Analysis Grade 12
Formal Definition & Axiom

The complete family of antiderivative functions whose instantaneous derivative equals the integrand $f(x)$, unified by the arbitrary constant of integration $C$.

Exemplar / Formula
$$\int x^n \, dx = \frac{x^{n+1}}{n+1} + C \quad (n \ne -1)$$
What It Does

It reconstructs total distance from velocity data, or total accumulated charge from electric current, reversing the derivative process.

How To Do It
  • 1 Identify each power term $x^n$.
  • 2 Add $1$ to the exponent ($n \to n + 1$).
  • 3 Divide by the new exponent ($n + 1$).
  • 4 Append the arbitrary integration constant $+ C$.
Worked Exemplum

Problem: Find the indefinite integral $\int (3x^2 + 4x - 5) \, dx$.

Solution: $\int 3x^2 dx = x^3$; $\int 4x dx = 2x^2$; $\int -5 dx = -5x$. Combine: $x^3 + 2x^2 - 5x + C$.

Q.E.D. ∎

Independent Variable

Linear & Piecewise Functions Grade 9
Formal Definition & Axiom

The input value of a function, which changes independently (usually time, graphed on the horizontal axis).

Inequality

Equations & Inequalities Grade 9
Formal Definition & Axiom

A mathematical statement comparing two expressions using relation symbols <, ≤, >, or ≥.

Inequality Reversal Property

Equations & Inequalities Grade 9
Formal Definition & Axiom

If a < b and c < 0, then ac > bc. Multiplying or dividing both sides of an inequality by a negative number reverses the direction of the inequality symbol.

Initial Value (a)

Algebraic Foundations & Modeling Grade 9
Formal Definition & Axiom

The value of the function when $x = 0$, representing the $y$-intercept. Because any nonzero base raised to the power of 0 equals 1 ($b^0 = 1$), $f(0) = a \cdot 1 = a$.

Exemplar / Formula
$$f(0) = a \cdot b^0 = a$$

Interpreting Correlation

Descriptive Statistics Grade 9
Formal Definition & Axiom

Core mathematical concept established in Module 2: Descriptive Statistics, Numerical Data on Two Variables.

Interpreting Quadratic Functions from Graphs and Tables

Quadratic Functions & Equations Grade 9
Formal Definition & Axiom

Core mathematical concept established in Module 4: Polynomial and Quadratic Expressions, Equations, and Functions, Quadratic Expressions, Equations, and Functions.

Interpreting the Standard Deviation

Descriptive Statistics Grade 9
Formal Definition & Axiom

Core mathematical concept established in Module 2: Descriptive Statistics, Calculating and Interpreting Measures of Center and Variability.

L

L — Concepts & Terminology

10 terms

Linear and Exponential Models—Comparing Growth Rates

Exponential Functions Grade 9
Formal Definition & Axiom

Core mathematical concept established in Module 3: Linear and Exponential Functions, Functions and Their Graphs.

LinearB

Quadratic Functions & Equations Grade 9
Formal Definition & Axiom

ExponentialC: Quadratic I looked at the difference in each output.

Linear Combination

Algebraic Foundations & Modeling Grade 9
Formal Definition & Axiom

An expression constructed from a set of terms by multiplying each term by a constant and adding the results.

Linear Slope-Intercept Form

/sloʊp ˈɪntərsɛpt/ • Latin: "intercipere" (to catch or cross between)
Algebraic Foundations & Modeling Grade 8
Formal Definition & Axiom

The canonical algebraic representation of a two-dimensional straight line, where $m$ signifies the constant rate of change (slope) and $b$ represents the coordinate value where the line intercepts the vertical y-axis ($(0, b)$).

Exemplar / Formula
$$y = mx + b \quad \left(m = \frac{\Delta y}{\Delta x} = \frac{y_2 - y_1}{x_2 - x_1}\right)$$
What It Does

It enables instant graphing and prediction of linear behaviors, allowing you to project future outcomes with a known starting point ($b$) and velocity ($m$).

How To Do It
  • 1 Calculate the slope $m$ by finding vertical change over horizontal change: $m = \frac{y_2 - y_1}{x_2 - x_1}$.
  • 2 Plot the starting y-intercept $(0, b)$ directly on the vertical axis.
  • 3 Use slope $m = \frac{\text{rise}}{\text{run}}$ to navigate from the intercept to subsequent points, and connect with a line.
Worked Exemplum

Problem: Find the slope-intercept equation of the line passing through $(2, 5)$ and $(4, 11)$.

Solution: Slope: $m = \frac{11 - 5}{4 - 2} = \frac{6}{2} = 3$. Find $b$: $5 = 3(2) + b \implies 5 = 6 + b \implies b = -1$. Equation: $y = 3x - 1$.

Q.E.D. ∎

Literal Equation

Equations & Inequalities Grade 9
Formal Definition & Axiom

An equation consisting predominantly of letters and variables representing known or unknown quantities.

Logarithms & Power Laws

/ˈlɒɡərɪðəm/ • Greek: "logos" (ratio) + "arithmos" (number)
Algebraic Foundations & Modeling Grade 11
Formal Definition & Axiom

The inverse mathematical function of exponentiation, answering the question: "To what exponent must the base $b$ be raised to produce the value $x$?"

Exemplar / Formula
$$\log_b(x) = y \iff b^y = x \quad (\log(xy) = \log x + \log y)$$
What It Does

It compresses astronomical multiplicative scales into manageable linear steps (Richter scale earthquakes, pH acidity, decibels of sound, compound interest).

How To Do It
  • 1 Product Rule: Sum of logs equals log of product: $\log(A) + \log(B) = \log(AB)$.
  • 2 Quotient Rule: Difference of logs equals log of quotient: $\log(A) - \log(B) = \log(A/B)$.
  • 3 Power Rule: Pull exponents out front as multipliers: $\log(A^k) = k \log(A)$.
Worked Exemplum

Problem: Condense into a single logarithm: $2\log_3(x) + \log_3(5)$.

Solution: Apply Power Rule: $\log_3(x^2) + \log_3(5)$. Apply Product Rule: $\log_3(5x^2)$.

Q.E.D. ∎

Look at these three tables

Algebraic Foundations & Modeling Grade 9
Formal Definition & Axiom

What do you notice about the three sets of data? Can you identify the type of function they represent? Students may observe some of the examples listed below.

Lost Solution

Algebraic Foundations & Modeling Grade 9
Formal Definition & Axiom

A valid solution that is accidentally eliminated by an invalid operation (such as dividing both sides by a variable expression that equals zero).

M

M — Concepts & Terminology

11 terms

Mathematical Modeling

Descriptive Statistics Grade 9
Formal Definition & Axiom

The process of choosing and using appropriate mathematics and statistics to analyze empirical situations, to understand them better, and to improve decisions.

Measures of Center: Mean, Median & Mode

/miːn ˈmiːdiən moʊd/ • Latin: "medianus" (of the middle)
Number Systems & Arithmetic Grade 6
Formal Definition & Axiom

Statistical metrics summarizing an entire data distribution into a single representative central value: the arithmetic average (Mean), the 50th percentile midpoint (Median), and the most frequent value (Mode).

Exemplar / Formula
$$\bar{x} = \frac{\sum_{i=1}^n x_i}{n}, \quad \text{Range} = \text{Max} - \text{Min}$$
What It Does

It distills large, noisy empirical datasets into actionable benchmark summaries for test scores, scientific experiments, climate averages, and economic indicators.

How To Do It
  • 1 Mean: Sum all values together, then divide by the total count $n$.
  • 2 Median: Arrange data in ascending numerical order and pick the exact middle value (or average the two middle values if $n$ is even).
  • 3 Mode: Identify the number that appears with highest frequency.
Worked Exemplum

Problem: Calculate the mean and median for the test score dataset: $\{80, 85, 90, 90, 100\}$.

Solution: Mean: $\frac{80+85+90+90+100}{5} = \frac{445}{5} = 89$. Median: Ordered middle value is $90$. Mode is $90$.

Q.E.D. ∎

Measuring Variability for Skewed Distributions (Interquartile Range)

Linear & Piecewise Functions Grade 9
Formal Definition & Axiom

Core mathematical concept established in Module 2: Descriptive Statistics, Calculating and Interpreting Measures of Center and Variability.

Measuring Variability for Symmetrical Distributions

Descriptive Statistics Grade 9
Formal Definition & Axiom

Core mathematical concept established in Module 2: Descriptive Statistics, Calculating and Interpreting Measures of Center and Variability.

Modeling a Context from a Verbal Description

Descriptive Statistics Grade 9
Formal Definition & Axiom

Core mathematical concept established in Module 5: A Synthesis of Modeling with Equations and Functions, Completing the Modeling Cycle.

Modeling a Context from Data

Descriptive Statistics Grade 9
Formal Definition & Axiom

Core mathematical concept established in Module 5: A Synthesis of Modeling with Equations and Functions, Completing the Modeling Cycle.

Modeling Relationships with a Line

Descriptive Statistics Grade 9
Formal Definition & Axiom

Core mathematical concept established in Module 2: Descriptive Statistics, Numerical Data on Two Variables.

More on Modeling Relationships with a Line

Descriptive Statistics Grade 9
Formal Definition & Axiom

Core mathematical concept established in Module 2: Descriptive Statistics, Numerical Data on Two Variables.

Multiplication Property of Equality

Equations & Inequalities Grade 9
Formal Definition & Axiom

If a = b, then ac = bc for any real number c.

Exemplar / Formula
$$\text{If } a = b, \text{ then } a \cdot c = b \cdot c$$
N

N — Concepts & Terminology

5 terms

Newton's Law of Cooling

Exponential Functions Grade 9
Formal Definition & Axiom

Core mathematical concept established in Module 3: Linear and Exponential Functions, Using Functions and Graphs to Solve Problems.

Non-Permissible Value

Algebraic Foundations & Modeling Grade 9
Formal Definition & Axiom

Any real number that causes a denominator in an expression to equal zero, making the expression undefined.

Note about lesson pace

Algebraic Foundations & Modeling Grade 9
Formal Definition & Axiom

Just like the last lesson, use the fact that the examples are very similar to reduce the amount of writing on the board.

Note about the lesson pace

Algebraic Foundations & Modeling Grade 9
Formal Definition & Axiom

Every new example or exercise in this lesson usually inserts just one more line of pseudocode into the previous exercise or example.

Now show a data plot for each

Algebraic Foundations & Modeling Grade 9
Formal Definition & Axiom

Now can you see the trends more clearly? Yes, it is obvious that the first is linear.

O

O — Concepts & Terminology

5 terms

Objects in Motion

Algebraic Foundations & Modeling Grade 9
Formal Definition & Axiom

Any object that is free falling or projected into the air without a power source is under the influence of gravity.

Open Circle

Equations & Inequalities Grade 9
Formal Definition & Axiom

A hollow dot on a number line representing an exclusive boundary that is not included in the solution set (< or >).

Ordered Pair

Algebraic Foundations & Modeling Grade 9
Formal Definition & Axiom

A pair of numbers (x, y) written in a specific order representing a unique point on a coordinate plane.

Order of Operations (PEMDAS / GEMS)

/ˈɔːrdər əv ˌɒpəˈreɪʃənz/ • Acronym: Parentheses, Exponents, Multiply/Divide, Add/Subtract
Number Systems & Arithmetic Grade 6
Formal Definition & Axiom

The universal algebraic precedence convention dictating the precise sequence in which arithmetic operations must be evaluated to ensure unambiguous solutions.

Exemplar / Formula
$$\text{Hierarchy: } \text{Groupings} \succ \text{Exponents} \succ \{\times, \div\} \succ \{+, -\}$$
What It Does

It eliminates mathematical chaos: without strict order of operations, an expression like $2 + 3 \times 4$ could be interpreted as either $20$ or $14$.

How To Do It
  • 1 Evaluate inside innermost Parentheses/Groupings first.
  • 2 Evaluate all Exponents and radical roots next.
  • 3 Compute all Multiplications and Divisions from Left to Right.
  • 4 Compute all Additions and Subtractions from Left to Right.
Worked Exemplum

Problem: Evaluate $6 + 4 \times (5 - 2)^2 \div 3$.

Solution: Groupings: $(5-2) = 3$. Exponents: $3^2 = 9$. Multiply/Divide Left-to-Right: $4 \times 9 = 36$, then $36 \div 3 = 12$. Addition: $6 + 12 = 18$.

Q.E.D. ∎
P

P — Concepts & Terminology

10 terms

Piecewise and Step Functions in Context

Exponential Functions Grade 9
Formal Definition & Axiom

Core mathematical concept established in Module 3: Linear and Exponential Functions, Using Functions and Graphs to Solve Problems.

Piecewise Functions

Exponential Functions Grade 9
Formal Definition & Axiom

Core mathematical concept established in Module 3: Linear and Exponential Functions, Transformations of Functions.

Piecewise Linear Function

Linear & Piecewise Functions Grade 9
Formal Definition & Axiom

A function defined by multiple linear segments, each covering a specific interval of time or domain. The overall graph looks like joined straight lines with corners.

Exemplar / Formula
$$f(x) = \begin{cases} -2x + 4 & \text{if } x < 1 \\ 3x - 1 & \text{if } x \ge 1 \end{cases}$$

Point of Intersection

Algebraic Foundations & Modeling Grade 9
Formal Definition & Axiom

A single point on the coordinate plane where two lines cross, representing the simultaneous solution.

Polynomial

Polynomials & Algebraic Expressions Grade 9
Formal Definition & Axiom

An expression consisting of variables and coefficients, constructed using only addition, subtraction, multiplication, and non-negative integer exponentiation.

Pose these questions

Descriptive Statistics Grade 9
Formal Definition & Axiom

Why does the first scatter plot result in an arch shape in the residual plot? The points in the scatter plot are not in a straight line.

Power Rule of Differentiation

/ˈpaʊər ruːl/ • Latin: "potentia" (power, exponent degree)
Calculus & Analysis Grade 12
Formal Definition & Axiom

An operational shortcut derived from the binomial theorem and difference quotient that computes the instantaneous rate of change of any monomial power function in a single algebraic step.

Exemplar / Formula
$$\frac{d}{dx}\left[x^n\right] = n x^{n - 1} \quad (n \in \mathbb{R})$$
What It Does

It bypasses lengthy limit difference quotient algebra, reducing derivative computation on polynomials to elementary mental arithmetic.

How To Do It
  • 1 Bring the existing exponent $n$ down in front to multiply the term.
  • 2 Subtract exactly $1$ from the power exponent ($n \to n - 1$).
  • 3 If the term has a leading constant $c$, multiply: $\frac{d}{dx}[c x^n] = c \cdot n x^{n-1}$.
Worked Exemplum

Problem: Differentiate $f(x) = 4x^3 - 5x^2 + 7x - 9$.

Solution: $f'(x) = 4(3)x^{3-1} - 5(2)x^{2-1} + 7(1)x^{1-1} - 0 = 12x^2 - 10x + 7$.

Q.E.D. ∎

Prime vs. Composite Numbers

/praɪm/ • Latin: "primus" (first, primordial, indivisible)
Number Systems & Arithmetic Grade 4
Formal Definition & Axiom

A natural number greater than $1$ is Prime if its only positive divisors are $1$ and itself. A number with more than two distinct positive factors is Composite.

Exemplar / Formula
$$\text{Prime: } \{n \in \mathbb{Z}^+ \mid \text{Factors}(n) = \{1, n\}\}$$
What It Does

Primes act as the multiplicative "atoms" of all mathematics: by the Fundamental Theorem of Arithmetic, every integer has a unique prime factorization.

How To Do It
  • 1 Check if $n \le 1$: $0$ and $1$ are neither prime nor composite.
  • 2 Test trial division by primes up to $\sqrt{n}$ ($2, 3, 5, 7 \dots$).
  • 3 If any divisor divides $n$ without remainder, $n$ is Composite; otherwise, it is Prime.
Worked Exemplum

Problem: Determine whether $29$ and $35$ are prime or composite.

Solution: Factors of $29$: $\{1, 29\} \implies$ Prime. Factors of $35$: $\{1, 5, 7, 35\} \implies$ Composite ($5 \times 7 = 35$).

Q.E.D. ∎

Pseudocode

Algebraic Foundations & Modeling Grade 9
Formal Definition & Axiom

Specifies the domain of the variable of x to be the set of integers.

Pythagorean Theorem

/pɪˌθæɡəˈriːən/ • Named after Pythagoras of Samos (c. 570–495 BC)
Geometry & Measurement Grade 8
Formal Definition & Axiom

A fundamental theorem of Euclidean geometry stating that in any right triangle, the area of the square erected upon the hypotenuse ($c$) equals the combined sum of the areas of the squares erected upon legs $a$ and $b$.

Exemplar / Formula
$$a^2 + b^2 = c^2 \iff c = \sqrt{a^2 + b^2}$$
What It Does

It unlocks straight-line distance calculations across two dimensions, forming the basis of navigation, construction, computer graphics, and coordinate geometry.

How To Do It
  • 1 Verify the triangle contains an exact $90^\circ$ right angle.
  • 2 Identify the hypotenuse ($c$), which is strictly opposite the right angle.
  • 3 Square the two known sides. To solve for hypotenuse: $c = \sqrt{a^2 + b^2}$. To solve for a leg: $a = \sqrt{c^2 - b^2}$.
Worked Exemplum

Problem: A right triangle has legs of length $6\text{ cm}$ and $8\text{ cm}$. Find the length of hypotenuse $c$.

Solution: $a^2 + b^2 = c^2 \implies 6^2 + 8^2 = c^2 \implies 36 + 64 = 100 \implies c = \sqrt{100} = 10\text{ cm}$.

Q.E.D. ∎
Q

Q — Concepts & Terminology

1 term

Quadratic Function

Quadratic Functions & Equations Grade 9
Formal Definition & Axiom

A polynomial function of degree 2 ($f(x) = ax^2 + bx + c$, with $a \neq 0$). Its graph forms a U-shaped parabola.

Exemplar / Formula
$$f(x) = ax^2 + bx + c \quad (a \ne 0)$$
R

R — Concepts & Terminology

11 terms

Ray

Algebraic Foundations & Modeling Grade 9
Formal Definition & Axiom

A continuous portion of the coordinate line extending indefinitely in one direction from an endpoint.

Recall

Quadratic Functions & Equations Grade 9
Formal Definition & Axiom

What does the graph of a quadratic equation look like?Remind students that when calculating squares in their calculator, they need to watch out for a common error: (-1)^{2}≠-1^{2}.

Rectangular Arrays & Repeated Addition

/əˈreɪ/ • Anglo-Norman: "arrai" (orderly systematic arrangement)
Number Systems & Arithmetic Grade 2
Formal Definition & Axiom

A geometric configuration of discrete objects aligned into identical horizontal rows and vertical columns, serving as the concrete foundation of multiplication.

Exemplar / Formula
$$\text{Total Items} = \sum_{i=1}^{r} c = r \times c$$
What It Does

It bridges counting single items to spatial two-dimensional grouping, proving that multiplication is rapid repeated addition.

How To Do It
  • 1 Count the number of horizontal lines (Rows, $r$).
  • 2 Count how many objects are situated in each single row (Columns, $c$).
  • 3 Add the row count $r$ times, or skip-count by $c$.
Worked Exemplum

Problem: Find the total items in an array containing $4$ rows with $5$ stars in each row.

Solution: Repeated addition of rows: $5 + 5 + 5 + 5 = 20$. The array contains exactly $20$ stars.

Q.E.D. ∎

Recurrence Relation

Equations & Inequalities Grade 9
Formal Definition & Axiom

An equation that expresses each element of a sequence as a function of the preceding elements (e.g., a_n = 2a_{n-1} + 5).

Recursive Formulas for Sequences

Exponential Functions Grade 9
Formal Definition & Axiom

Core mathematical concept established in Module 3: Linear and Exponential Functions, Linear and Exponential Sequences.

Relationships Between Two Numerical Variables

Descriptive Statistics Grade 9
Formal Definition & Axiom

Core mathematical concept established in Module 2: Descriptive Statistics, Numerical Data on Two Variables.

Reversible Step

Equations & Inequalities Grade 9
Formal Definition & Axiom

An algebraic operation that preserves the exact solution set, such that applying its inverse returns the original equation.

Right Triangle Trigonometry (SOH-CAH-TOA)

/ˌtrɪɡəˈnɒmətri/ • Greek: "trigonon" (triangle) + "metron" (measure)
Trigonometric Functions Grade 10
Formal Definition & Axiom

Fundamental trigonometric ratios relating the acute reference angle ($\theta$) of a right triangle to dimensionless quotients of its side lengths.

Exemplar / Formula
$$\sin\theta = \frac{\text{Opp}}{\text{Hyp}}, \quad \cos\theta = \frac{\text{Adj}}{\text{Hyp}}, \quad \tan\theta = \frac{\text{Opp}}{\text{Adj}}$$
What It Does

It enables the measurement of inaccessible heights and distances (surveying mountains, celestial navigation, architectural load angles) from a single angle and distance.

How To Do It
  • 1 Anchor your perspective at the acute reference angle $\theta$.
  • 2 Label the three sides: Hypotenuse (longest side opposite $90^\circ$), Opposite (across from $\theta$), and Adjacent (next to $\theta$).
  • 3 Select the matching ratio from SOH-CAH-TOA based on your known and unknown sides, then solve.
Worked Exemplum

Problem: In a right triangle, angle $\theta$ has an opposite side of $5\text{ cm}$ and hypotenuse of $13\text{ cm}$. Find $\sin\theta$ and $\tan\theta$.

Solution: $\sin\theta = \frac{\text{Opp}}{\text{Hyp}} = \frac{5}{13}$. Adjacent side: $\sqrt{13^2 - 5^2} = \sqrt{144} = 12$. Therefore, $\tan\theta = \frac{\text{Opp}}{\text{Adj}} = \frac{5}{12}$.

Q.E.D. ∎

Roots / Zeros

Algebraic Foundations & Modeling Grade 9
Formal Definition & Axiom

The input values that cause an expression or function to evaluate to zero.

S

S — Concepts & Terminology

14 terms

Sample Response

Algebraic Foundations & Modeling Grade 9
Formal Definition & Axiom

We can tell that this problem involves a geometric sequence because we are multiplying each term by either 1.

Second Differences

Quadratic Functions & Equations Grade 9
Formal Definition & Axiom

The differences between consecutive first differences. In any quadratic sequence with equal intervals, the second differences are constant!

Set-Builder Notation

Algebraic Foundations & Modeling Grade 9
Formal Definition & Axiom

A mathematical shorthand notation describing a set by stating the properties that its members must satisfy, e.g., {x | x > -9}.

Solution Set

Equations & Inequalities Grade 9
Formal Definition & Axiom

The set of all values from the domain that make an open sentence or equation true.

Exemplar / Formula
$$S = \{x \in \mathbb{R} \mid 2x + 5 = 11\} = \{3\}$$

Solving Basic One-Variable Quadratic Equations

Quadratic Functions & Equations Grade 9
Formal Definition & Axiom

Core mathematical concept established in Module 4: Polynomial and Quadratic Expressions, Equations, and Functions, Quadratic Expressions, Equations, and Functions.

Standard Form of a Polynomial

Polynomials & Algebraic Expressions Grade 9
Formal Definition & Axiom

A polynomial written such that its terms are placed in descending order of degree from left to right.

Exemplar / Formula
$$P(x) = a_n x^n + a_{n-1} x^{n-1} + \dots + a_1 x + a_0$$

Stretching and Shrinking Graphs of Functions

Quadratic Functions & Equations Grade 9
Formal Definition & Axiom

Core mathematical concept established in Module 4: Polynomial and Quadratic Expressions, Equations, and Functions, Function Transformations and Modeling.

Subject of a Formula

Equations & Inequalities Grade 9
Formal Definition & Axiom

The variable that is isolated by itself on one side of an equation with a coefficient of 1.

Substitution Method

Equations & Inequalities Grade 9
Formal Definition & Axiom

An algebraic technique where one variable is isolated and substituted into the other equation.

Summarizing Bivariate Categorical Data

Descriptive Statistics Grade 9
Formal Definition & Axiom

Core mathematical concept established in Module 2: Descriptive Statistics, Categorical Data on Two Variables.

T

T — Concepts & Terminology

13 terms

Tabular Multiplication (Box Method)

Algebraic Foundations & Modeling Grade 9
Formal Definition & Axiom

A geometric organizer where terms of one polynomial form rows and terms of the other form columns, computing all partial products systematically.

Target Inversion

Algebraic Foundations & Modeling Grade 9
Formal Definition & Axiom

Setting an explicit sequence formula equal or unequal to a desired threshold target and solving backwards for the initial term.

Taxable Income

Algebraic Foundations & Modeling Grade 9
Formal Definition & Axiom

The amount of gross income used to calculate tax liability, after subtracting allowable exemptions and deductions.

Term

Algebraic Foundations & Modeling Grade 9
Formal Definition & Axiom

A single mathematical number, variable, or product of numbers and variables separated by addition or subtraction operators.

Test Point

Equations & Inequalities Grade 9
Formal Definition & Axiom

A coordinate pair (not on the boundary line) substituted into an inequality to determine which half-plane contains solutions.

The Power of Exponential Growth

Exponential Functions Grade 9
Formal Definition & Axiom

Core mathematical concept established in Module 3: Linear and Exponential Functions, Linear and Exponential Sequences.

Transformations of the Quadratic Parent Function, f(x)=x^{2}

Quadratic Functions & Equations Grade 9
Formal Definition & Axiom

Core mathematical concept established in Module 4: Polynomial and Quadratic Expressions, Equations, and Functions, Function Transformations and Modeling.

Translating Graphs of Functions

Quadratic Functions & Equations Grade 9
Formal Definition & Axiom

Core mathematical concept established in Module 4: Polynomial and Quadratic Expressions, Equations, and Functions, Function Transformations and Modeling.

Trinomial

/ˈfæk.tər.ɪŋ/ • Latin: "factor" (a maker, doer, or constituent part)
Polynomials & Algebraic Expressions Grade 9
Formal Definition & Axiom

A polynomial with exactly three terms, such as ax² + bx + c.

Exemplar / Formula
$$x^2 + (p + q)x + pq = (x + p)(x + q)$$
What It Does

By applying the Zero Product Property ($AB = 0 \implies A=0 \text{ or } B=0$), factoring converts complex polynomial expressions into simple solvable linear equations.

How To Do It
  • 1 Look for two integers $p$ and $q$ that multiply to constant $c$ ($p \times q = c$) and add to middle coefficient $b$ ($p + q = b$).
  • 2 Construct the binomials: $(x + p)(x + q)$.
  • 3 Check work by expanding via FOIL (First, Outside, Inside, Last).
Worked Exemplum

Problem: Factor the polynomial $x^2 + 7x + 12$.

Solution: Find two numbers that multiply to $12$ and add to $7$: $3 \times 4 = 12$ and $3 + 4 = 7$. Factored form: $(x + 3)(x + 4)$.

Q.E.D. ∎

Truth Value

Equations & Inequalities Grade 9
Formal Definition & Axiom

The property of a mathematical sentence indicating whether it is True or False under a specific substitution.

U

U — Concepts & Terminology

4 terms

Unit Fractions & Rational Partitioning

/ˈjuːnɪt ˈfrækʃən/ • Latin: "fractio" (a breaking into fragments)
Fractions & Rational Numbers Grade 3
Formal Definition & Axiom

A rational quantity formed by partitioning a single whole into $b$ congruent, equal-sized pieces, where the fraction represents exactly one of those partitioned segments.

Exemplar / Formula
$$\text{Unit Fraction} = \frac{1}{b} \quad (b \in \mathbb{Z}^+)$$
What It Does

It establishes the fundamental atomic building block of all rational numbers: any non-unit fraction $\frac{a}{b}$ is simply $a$ copies of the unit fraction $\frac{1}{b}$.

How To Do It
  • 1 Verify the whole unit is divided into segments of strictly equal size/length.
  • 2 Count the total number of segments to determine the denominator ($b$).
  • 3 Isolate or shade exactly 1 segment to represent $\frac{1}{b}$.
Worked Exemplum

Problem: Express the fraction $\frac{5}{8}$ as an iteration of its underlying unit fraction.

Solution: The unit fraction is $\frac{1}{8}$. Thus: $\frac{5}{8} = \frac{1}{8} + \frac{1}{8} + \frac{1}{8} + \frac{1}{8} + \frac{1}{8} = 5 \times \frac{1}{8}$.

Q.E.D. ∎

Unit Rate

/prəˌpɔːʃəˈnæləti/ • Latin: "pro portione" (according to the share)
Algebraic Foundations & Modeling Grade 9, Grade 7
Formal Definition & Axiom

A rate in which the second quantity in the comparison is one unit (e.g., 25 pages per minute).

Exemplar / Formula
$$y = kx \implies k = \frac{y}{x}$$
What It Does

It describes uniform rate behaviors: speed ($d = rt$), wage rates ($\text{Pay} = r \times \text{Hours}$), scaling recipes, and currency conversion.

How To Do It
  • 1 Pick any non-zero ordered coordinate pair $(x, y)$ from a proportional table or graph.
  • 2 Divide the dependent variable $y$ by independent variable $x$: $k = \frac{y}{x}$.
  • 3 Verify that all other pairs $(x_i, y_i)$ yield the identical quotient $k$.
Worked Exemplum

Problem: A car travels $165\text{ miles}$ in $3\text{ hours}$ at constant speed. Find the constant of proportionality and the equation relating distance ($y$) and hours ($x$).

Solution: $k = \frac{y}{x} = \frac{165}{3} = 55\text{ mph}$. Direct proportional equation: $y = 55x$.

Q.E.D. ∎

Using the Quadratic Formula

Quadratic Functions & Equations Grade 9
Formal Definition & Axiom

Core mathematical concept established in Module 4: Polynomial and Quadratic Expressions, Equations, and Functions, Using Different Forms for Quadratic Functions.

V

V — Concepts & Terminology

3 terms

Velocity

Algebraic Foundations & Modeling Grade 9
Formal Definition & Axiom

The speed of an object in a given direction, corresponding to signed slope on a displacement graph.

Volume of Rectangular Prisms

/ˈvɒljuːm/ • Latin: "volumen" (roll, scroll, 3D cubic capacity)
Geometry & Measurement Grade 5
Formal Definition & Axiom

The total measure of three-dimensional space enclosed within a solid boundary, quantified as the aggregate number of unit cubes ($1 \times 1 \times 1$) that pack the interior without gaps.

Exemplar / Formula
$$V = l \times w \times h = B \times h$$
What It Does

It measures the physical capacity of solid 3D structures (such as storage containers, shipping boxes, or liquid tanks).

How To Do It
  • 1 Measure the length ($l$) and width ($w$) of the rectangular base to find base area ($B = l \times w$).
  • 2 Measure the perpendicular vertical height ($h$) of the prism.
  • 3 Multiply base area by height: $V = B \times h$. Units are always cubic ($\text{cm}^3, \text{in}^3, \text{m}^3$).
Worked Exemplum

Problem: Find the volume of a rectangular prism with length $6\text{ cm}$, width $4\text{ cm}$, and height $5\text{ cm}$.

Solution: $V = l \times w \times h = 6 \times 4 \times 5 = 24 \times 5 = 120\text{ cm}^3$.

Q.E.D. ∎
W

W — Concepts & Terminology

2 terms

Why Do Banks Pay YOU to Provide Their Services?

Exponential Functions Grade 9
Formal Definition & Axiom

Core mathematical concept established in Module 3: Linear and Exponential Functions, Linear and Exponential Sequences.

Why Stay with Whole Numbers?

Exponential Functions Grade 9
Formal Definition & Axiom

Core mathematical concept established in Module 3: Linear and Exponential Functions, Functions and Their Graphs.

X

X — Concepts & Terminology

1 term
Z

Z — Concepts & Terminology

1 term

Zero-Product Property

Equations & Inequalities Grade 9
Formal Definition & Axiom

If the product of two real numbers is zero, then at least one of the numbers must be zero: ab = 0 implies a = 0 or b = 0.

Exemplar / Formula
$$\text{If } A \cdot B = 0, \text{ then } A = 0 \text{ or } B = 0$$