PSAT Math Multiple-Choice Question 723: Answer and Explanation

Question: 723

Which of the following operations could be performed on both sides of the inequality -2x > 4 to require the direction of the inequality sign be changed while keeping x on the left-hand side of the inequality?

• A. Add 4
• B. Subtract 7
• C. Divide by -2
• D. Multiply by 12

Correct Answer: C

Explanation:

(C) Multiplying or dividing an inequality by a negative number requires that the direction of the inequality sign be reversed. The other operations mentioned do not do so. Here is how the inequality can be solved when dividing by -2:

If you try some sample values that work for x, such as -3 or -5, you will see that the inequality is true.