PSAT Math Multiple-Choice Question 225: Answer and Explanation

Question: 225

The following quadratic equations are all representations of the graph shown above. Which equation could you use to find the minimum value of the function without doing any additional work?

• A.
• B.
• C.
• D.

Correct Answer: A

Explanation:

A

Difficulty: Easy

Category: Passport to Advanced Math/Quadratics

Getting to the Answer: The minimum value of a quadratic function is equal to the y-value of the vertex of its graph, so vertex form, y = a(x - h)² + k, reveals the minimum without doing any additional work. Choice (A) is the only equation written in this form and therefore must be correct. The minimum value of this function is .