Digital PSAT Math Practice Question 230: Answer and Explanation

Question: 230

A line has the equation y - 4x = 5. What is the slope of a line that is perpendicular to this line?

• A. -4
• B.
• C.
• D. 4

Correct Answer: B

Explanation:

(B) First, get this line in slope-intercept form so that you can easily tell what the slope of this line is. You can do so by adding 4x to both sides to get the equation y = 4x + 5. The slope of this line is 4. The slope of a line perpendicular to this one will have a slope that is the negative reciprocal of this, , which matches (B).