Question

One side of a rectangle is 4 inches longer than the other side. The area of the rectangle is 21 square inches. Find the lengths of each side.

Answer 1

l = 7 in; w = 3 in

Explanation:

The formula for the area of a rectangle is

A = lw

Data:

A = 21 in²

l = w + 4

Calculation:

21 = (w + 4) × w

21 = w² + 4w

w² + 4w - 21 = 0

(w + 7)(w - 3) = 0

w + 7 = 0 w - 3 = 0

w = -7 w = 3

We reject the negative value, so w = 3 in.

21 = l × 3

l = 7

The rectangle is 7 in long and 3 in wide.