SAT Math Multiple Choice Question 592: Answer and Explanation
7. The x-coordinates of the solutions to a system of equations are –4 and 2. Which of the following could be the system?
Correct Answer: D
Category: Passport to Advanced Math / Quadratics
Strategic Advice: The solution to a system of equations is the point(s) where their graphs intersect. You could solve this question algebraically, one system at a time, but this is not time efficient. Instead, graph each pair of equations in your graphing calculator and look for the graphs that intersect at x = –4 and x = 2.
Getting to the Answer: The graphs of the equations in A and B don't intersect at all, so you can eliminate them right away. The graphs in C intersect, but both points of intersection have a positive x-coordinate. This means (D) must be correct. The graph looks like: