The length of a rectangle is 3 inches more than its width. The area of
the rectangle is 40 square inches. What is the length, in inches, of the
rectangle?
(1) 5 (3) 8.5
(2) 8 (4) 11.5

Question

The length of a rectangle is 3 inches more than its width. The area of 
the rectangle is 40 square inches. What is the length, in inches, of the 
rectangle?
(1) 5 (3) 8.5
(2) 8 (4) 11.5

anonymous · Answer

Set L = W + 3

Area equals L * W

So (W+3)*W = 40   (put everything on one side)

 w^2 +3w -40 = 0   (factor)

(w+8)(w-5) = 0

W = 5, -8

Since W can't be negative, W = 5

If W =5, Then L = W + 3 = 8 and A = 5 * 8 = 40