⚡ QUADRATIC FORMULA: x = (−b ± √(b²−4ac)) / 2a · Identify a, b, c first
⚡ DISCRIMINANT = b²−4ac · ONE solution → Δ = 0 · TWO solutions → Δ > 0 · NONE → Δ < 0
⚡ REMAINDER THEOREM: remainder = f(divisor root) → divide by (x−c), just compute f(c)
⚡ LOG PRODUCT RULE: logₐM + logₐN = logₐ(MN) · Always CHECK domain (argument > 0)!
⚡ SAME BASE TRICK: rewrite both sides as powers of 2 → set exponents equal
⚡ FOIL then REPLACE i² = −1 · Real part: subtract i² terms · Imaginary part: collect i terms
⚡ RATIONAL EXPONENT: xm/n = (ⁿ√x)m · Denominator = root, Numerator = power
⚡ GEO SUM: Sₙ = a₁(1 − rⁿ) / (1 − r) · Use this when r ≠ 1
⚡ VERTEX FORM: y = a(x − h)² + k · Vertex = (h, k) · a > 0 → opens UP · a < 0 → opens DOWN
A
Vertex (3, 5) · opens upward
B
Vertex (−3, 5) · opens upward
C
Vertex (3, −5) · opens downward
D
Vertex (3, 5) · opens downward
⚡ INVERSE: SWAP x and y, then solve for y · f⁻¹ undoes what f does
⚡ CONE VOLUME = (1/3)πr²h · Cone = ⅓ of a cylinder with same base and height
⚡ PERP BISECTOR: (1) Find midpoint (2) Find slope of AB (3) Perpendicular slope = −1/m
⚡ SOH-CAH-TOA · sin=Opp/Hyp · cos=Adj/Hyp · tan=Opp/Adj · Use Pythagoras first!
B
adj = 18, cos θ = 18/25
C
adj = 24, cos θ = 24/25
D
adj = 22, cos θ = 22/25
⚡ STANDARD CIRCLE: (x−h)² + (y−k)² = r² · Center = (h, k) · WATCH the sign inside the brackets!
⚡ REFLECTIONS: Over y-axis: (x,y)→(−x,y) · Over x-axis: (x,y)→(x,−y) · Only ONE coordinate flips!
⚡ SPHERE SURFACE AREA = 4πr² · "Four times pi r squared" — not πr²!
⚡ tan(angle) = OPPOSITE / ADJACENT · Height is opposite · Distance from base is adjacent
⚡ SUPPLEMENTARY = 180° · Set up: ∠1 + ∠2 = 180 → solve for x → substitute back
⚡ DILATION from origin: (x, y) → (kx, ky) · Multiply BOTH coordinates by scale factor k
⚡ SECTOR AREA = (θ/360°) × πr² · Fraction of full circle area — same idea as arc length!