Digital PSAT Math Practice Question 309: Answer and Explanation

Question: 309

What are the possible values of b in the system of equations below?

• A. –3, –7
• B. –1, 7
• C. 3, –1
• D. 3, 7

Correct Answer: B

Explanation:

(B) Use substitution to solve for a:

b = 2a + 1 and b + 2 = a² → (2a + 1) + 2 = a²

2a + 3 = a²→

a² - 2a - 3 = 0 → (a - 3)(a + 1) = 0

When a = 3, b = 7, and when a = -1, b = -1.