PSAT Math Multiple-Choice Question 208: Answer and Explanation

Question: 208

If a line that passes through the ordered pairs (4 - c, 2 c) and (- c, -8) has a slope of , what is the value of c ?

• A. - 5
• B. - 3
• C. - 2
• D. 2

Correct Answer: B

Explanation:

B

Difficulty: Medium

Category: Heart of Algebra/Linear Equations

Getting to the Answer: Given two points (even when the coordinates are variables), the slope of the line between the points can be found using the formula . You are given a numerical value for the slope and a pair of ordered pairs that have variables in them. To find the value of c, plug the points into the slope formula and then solve for c. Be careful of all the negative signs:

Choice (B) is correct.