PSAT Math Multiple-Choice Question 504: Answer and Explanation

Question: 504

Which of the following is a solution to the equation p² + 20p + 75 = 0?

• A. –75
• B. –15
• C. 0
• D. 20

Correct Answer: B

Explanation:

B

The question asks for a solution to the equation. Since the question asks for a specific value and the answers contain numbers in increasing order, plug in the answers and look for the answer choice that makes the equation true. Begin by labeling the answers as "p" and start with (B), –15. Plug –15 into the equation for x to get (–15)² + 20(–15) + 75 = 0. The equation simplifies to 225 – 300 + 75 = 0 or –75 + 75 = 0. Since this is true, stop here. The correct answer is (B).