PSAT Math Multiple-Choice Question 171: Answer and Explanation

Question: 171

The figure above shows the graph of f(x). For which value(s) of x does f(x) equal 0?

• A. - 3 and 3
• B. - 1 and 1
• C. - 1, 1, and 2
• D. 2 only

Correct Answer: B

Explanation:

B

Difficulty: Easy

Category: Passport to Advanced Math/Functions

Getting to the Answer: When using function notation, f(x) is simply another way of saying y, so this question is asking you to find the value(s) of x for which y = 0, or in other words, where the graph crosses the x-axis. Don't be tempted by the flat parts of the graph—they have a slope of 0, but the function itself does not equal 0 here (it equals -4). The graph crosses the x-axis at the points (-1, 0) and (1, 0), so the values of x for which f(x) = 0 are -1 and 1. (B) is correct.