PSAT Math Multiple-Choice Question 490: Answer and Explanation

Question: 490

If the graph of line n in the xy-plane above is represented by the equation y = mx + c, where m and c are constants, which of the following set of inequalities is true about m and c?

• A.
• B.
• C.
• D.

Correct Answer: D

Explanation:

D

The question asks for a system of inequalities that represents the graph. The graph is represented by the equation y = mx + c where m is the slope and c is the y-intercept. The graph has a negative slope and a y-intercept of 2. Eliminate answer choices that do not match this information. Start with either the slope or the y-intercept and use Process of Elimination on the answers. For example, if the slope must be negative, (B) and (C) can be eliminated, as those have positive values for m. Next, focus on the values of c in the remaining choices, values that represent the y-intercept. Choice (A) has a y-intercept of less than –4, so eliminate (A). It is also fine to start by eliminating choices with the wrong y-intercept before moving on to the slope. Either way, the correct answer is (D).