PSAT Math Multiple-Choice Question 313: Answer and Explanation

Question: 313

A line, t, is perpendicular to and passes through the point (3, 5). What is the equation of line t ?

• A.
• B.
• C.
• D.

Correct Answer: A

Explanation:

A

Difficulty: Medium

Getting to the Answer: The first useful piece of information is that the slope of the line perpendicular to line t is . Perpendicular lines have negative reciprocal slopes, so the slope of line t is . Eliminate (B) and (D) because they have the incorrect slopes.

Plug the values for the slope and the coordinate point (3, 5) into the slope-intercept equation to solve for b:

Eliminate (C) because it does not have the correct y-intercept. Choice (A) is correct.