PSAT Math Multiple-Choice Question 173: Answer and Explanation

Question: 173

At what value(s) of x do the graphs of y = -2 x + 1 and y = 2 x² + 5 x + 4 intersect?

• A.
• B.
• C.
• D.

Correct Answer: B

Explanation:

B

Difficulty: Medium

Category: Passport to Advanced Math/Quadratics

Getting to the Answer: Although this question asks where the graphs intersect, it is not necessary to actually graph them. The point(s) at which the two graphs intersect are the points where the two equations are equal to each other. Therefore, set the equations equal and use algebra to solve for x. Because the question only asks for the x-values, you don't need to substitute the results back into the equations to solve for y.

Now that the equation is factored, solve for x:

Choice (B) is correct.