PSAT Math Multiple-Choice Question 74: Answer and Explanation

Question: 74

If ABCD is a square, what is the area of the square?

• A. 2
• B. 4
• C. 20
• D. 25

Correct Answer: D

Explanation:

D

The question asks for the area of square ABCD. The lengths of the sides are given as variable expressions instead of numbers, so solve for x first. In a square, all sides are equal, so 2x + 1 = x + 3. First, subtract 1 from each side so that 2x = x + 2. Then subtract x from each side so that x = 2. Plug that value of x into the expression x + 3 to get 2 + 3 = 5, which is the length of each side. The formula for the area of a square is A = (length)(width), so the area is (5)(5) = 25. The correct answer is (D).