PSAT Math Multiple-Choice Question 196: Answer and Explanation

Question: 196

Where will the line shown in the graph above intersect the x-axis?

• A. - 5.5
• B. - 5
• C. - 4.5
• D. - 4

Correct Answer: B

Explanation:

B

Difficulty: Easy

Category: Heart of Algebra/Linear Equations

Getting to the Answer: Finding an x-intercept is easy when you know the equation of the line—it's the value of x when y is 0. Notice that the answer choices are very close together. This means you shouldn't just estimate visually. Take the time to do the math. Everything you need to write the equation is shown on the graph—just pay careful attention to how the grid lines are labeled. The y-intercept is 10 and the line rises 2 units and runs 1 unit from one point to the next, so the slope is This means the equation of the line, in slope-intercept form, is y = 2 x + 10. Now, set the equation equal to zero and solve for x:

The line will intersect the x-axis at -5, which is (B).