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Polynomial expressions and factoring — ACT practice questions

Polynomial expressions and factoring on the ACT Mathematics test covers expanding products, rewriting polynomials in equivalent factored form, and finding zeros of a polynomial that factors cleanly. A student has to expand a squared binomial, factor a quadratic trinomial, and count the distinct real zeros of a higher-degree polynomial, often after treating it as a quadratic in a squared variable. Items usually ask which expression is equivalent to a given polynomial or how many distinct real zeros it has. Answer choices look like near-miss expansions and factorizations that differ by a sign, a middle term, or a repeated root.

  • Section: Mathematics 45 questions on the paper
  • 58 practice questions in the app

Sample questions

Question 1

Which of the following expressions is equivalent to (2x+3)2(2x+3)^2?

  1. A4x2+12x+94x^2+12x+9
  2. B4x2+94x^2+9
  3. C4x2+6x+94x^2+6x+9
  4. D2x2+12x+92x^2+12x+9
Show answer

Answer: A — 4x2+12x+94x^2+12x+9

(2x+3)2=(2x)2+2(2x)(3)+32=4x2+12x+9(2x+3)^2=(2x)^2+2(2x)(3)+3^2=4x^2+12x+9.

Question 2

Which of the following expressions is equivalent to 10t217t+610t^2-17t+6?

  1. A(5t6)(2t1)(5t-6)(2t-1)
  2. B(5t3)(2t2)(5t-3)(2t-2)
  3. C(10t3)(t2)(10t-3)(t-2)
  4. D(5t+6)(2t+1)(5t+6)(2t+1)
Show answer

Answer: A — (5t6)(2t1)(5t-6)(2t-1)

Expanding (5t6)(2t1)(5t-6)(2t-1) gives 10t25t12t+610t^2-5t-12t+6. Combining the middle terms yields 10t217t+610t^2-17t+6.

Question 3

How many distinct real zeros does p(x)=x45x2+4p(x)=x^4-5x^2+4 have?

  1. A0
  2. B2
  3. C3
  4. D4
Show answer

Answer: D — 4

Treat the expression as a quadratic in x2x^2: x45x2+4=(x21)(x24)x^4-5x^2+4=(x^2-1)(x^2-4). Thus, the distinct real zeros are 2,1,1,-2,-1,1, and 2, for a total of 4.

Practice 58 Polynomial expressions and factoring questions in the app

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