PSAT Math Multiple-Choice Question 39: Answer and Explanation

Question: 39

If 3^{x + 2} = 243, what is the value of x?

• A. 1
• B. 2
• C. 3
• D. 4

Correct Answer: C

Explanation:

C

The question asks for the value of the variable x in the given equation. Since the question asks for a specific value and the answers contain numbers in increasing order, plug in the answers. Begin by labeling the answers as x and starting with (C). Plug x = 3 into the equation and work the steps of the question. The equation becomes 3³⁺² = 243, or 3⁵ = 243. This simplifies to 243 = 243, which is true. Since (C) works, stop here. The correct answer is (C).