PSAT Math Multiple-Choice Question 473: Answer and Explanation

Question: 473

Which of the following is an equivalent form of 4x² - 8x + 64 = 0?

• A. (x - 2)² = -12
• B. (x + 2)² = 12
• C. (x - 1)² = -15
• D. (x + 1)² = 15

Correct Answer: C

Explanation:

C

Difficulty: Hard

Category: Completing the Square

Getting to the Answer: First divide both sides by 4, so that 4x² - 8x + 64 = 0 becomes x² - 2x + 16 =0. Notice that this cannot be solved by factoring, so use the completing the square method:

Therefore, (C) is correct.