Official ACT Prep · 2024 Edition

ACT Math
Master Quiz

20 Essential Problems · All Core Topics · Expert Explanations

20
Questions
60min
Timer
5
Topics
Pre-Algebra Algebra Geometry Trigonometry Statistics Coordinate Geometry
Core Concepts & Formulas

Study Before You Test

Master these key concepts and memorize critical formulas

TOPIC 01 · PRE-ALGEBRA
Number Properties & Ratios
Integers include positive, negative, and zero. A prime number has exactly two distinct factors: 1 and itself. A composite number has more than two factors. Ratios compare two quantities, and proportions state two ratios are equal.
LCM(a,b) = (a × b) / GCF(a,b)
Percent Change = [(New − Old) / Old] × 100%
LCM & GCF Prime factorization Percent → decimal ÷ 100 Cross-multiplication
TOPIC 02 · ALGEBRA
Linear & Quadratic Equations
Solve linear equations by isolating the variable. For systems of equations, use substitution or elimination. Quadratics can be solved by factoring, completing the square, or using the quadratic formula.
Quadratic: ax² + bx + c = 0
x = (−b ± √(b²−4ac)) / 2a
Discriminant: D = b²−4ac
D > 0: two real roots D = 0: one root D < 0: no real roots FOIL
TOPIC 03 · FUNCTIONS
Function Notation & Transformations
f(x) represents the output when input is x. Domain is all valid inputs; range is all possible outputs. Composite functions: (f∘g)(x) = f(g(x)). Inverse function f⁻¹(x) reverses the operation.
Slope: m = (y₂ − y₁) / (x₂ − x₁)
Slope-intercept: y = mx + b
Point-slope: y − y₁ = m(x − x₁)
Vertical line test f(g(x)) composition Parallel: same slope Perpendicular: m₁×m₂ = −1
TOPIC 04 · GEOMETRY
Area, Volume & Angle Theorems
Know formulas for all 2D and 3D shapes. Triangles: angles sum to 180°. Exterior angle = sum of two non-adjacent interior angles. Similar triangles have proportional sides. The Pythagorean theorem applies to right triangles.
Circle: A = πr², C = 2πr
Cylinder: V = πr²h
Pythagorean: a² + b² = c²
3-4-5 triangle 5-12-13 triangle 30-60-90: 1:√3:2 45-45-90: 1:1:√2
TOPIC 05 · TRIGONOMETRY
SOH-CAH-TOA & Unit Circle
Sine, cosine, and tangent relate angles to side ratios in a right triangle. Remember SOH-CAH-TOA. Know key angles: 0°, 30°, 45°, 60°, 90°. The Law of Sines and Law of Cosines extend trig to non-right triangles.
sin θ = opposite/hypotenuse
cos θ = adjacent/hypotenuse
tan θ = opposite/adjacent = sin θ/cos θ
sin²θ + cos²θ = 1
sin 30° = 1/2 cos 60° = 1/2 tan 45° = 1 sin 90° = 1
TOPIC 06 · COORDINATE GEOMETRY
Distance, Midpoint & Circles
The coordinate plane uses (x, y) pairs. Distance formula derives from the Pythagorean theorem. Midpoint finds the center of a segment. The standard equation of a circle centered at (h, k) with radius r.
Distance: d = √[(x₂−x₁)² + (y₂−y₁)²]
Midpoint: ((x₁+x₂)/2 , (y₁+y₂)/2)
Circle: (x−h)² + (y−k)² = r²
Standard form ax+by=c Quadrants I-IV Parabola: y=ax²+bx+c
TOPIC 07 · STATISTICS & PROBABILITY
Mean, Median, Mode & Probability
Mean is the arithmetic average. Median is the middle value when sorted. Mode is the most frequent value. Range = max − min. Probability of an event = favorable outcomes / total outcomes. Independent events: P(A and B) = P(A) × P(B).
Mean = Σx / n
P(A or B) = P(A) + P(B) − P(A∩B)
Combinations: C(n,r) = n! / (r!(n−r)!)
Ordered data for median Standard deviation Box plot Complement: P(not A) = 1−P(A)
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