AP Exam KitAP Precalculus
Unit 11.11 Equivalent RepresentationsNo calculator

Which form of p(x)=2x38xp(x)=2x^3-8x most directly reveals all real zeros?

  1. 2x(x2)(x+2)2x(x-2)(x+2)
  2. 2(x34x)2(x^3-4x)
  3. 2x(x2+4)2x(x^2+4)
  4. 2(x2)32(x-2)^3

Answer and derivation

Correct answer: A

The factored form displays zeros 2,0,2-2,0,2.

  1. 2x38x=2x(x24)2x^3-8x=2x(x^2-4).
  2. x24=(x2)(x+2)x^2-4=(x-2)(x+2).
  3. Each linear factor directly reveals one real zero.

Why the other options fail

A
Correct complete factorization.
B
It is equivalent but does not reveal the zeros directly.
C
The sign in the quadratic factor is wrong.
D
Expanding does not reproduce the polynomial.

Common misconception: Equivalent forms can be useful for different features; factored form is best for zeros.

China/AP bridge: AP questions often ask which form is useful, not merely whether algebraic manipulation is valid.

Original author: AP Exam KitMathematical review: REV-2D-03