PSAT Math Multiple-Choice Question 445: Answer and Explanation

Question: 445

Which equation does NOT have a solution at x = -4?

• A.
• B.
• C.
• D.

Correct Answer: A

Explanation:

A

Difficulty: Medium

Getting to the Answer: This question can be solved two ways. One is to factor each choice and solve for the solutions, and whichever does not have a solution of x = -4 is correct. Another way is to plug in x = -4 for each choice; if the equation does not equal 0, then that choice is correct. Luckily, plugging x = -4 into the first choice results in 64 and not 0. Choice (A) factored would be (x - 4)², so its only unique root is x = 4. Hence, (A) is correct.