Question

The width of a painting is 4 inches less than the length , and the surface area is 320 square inches. Find the length.

Answer 1

The length is 20 inches. 20 times 16 equals 320 so the length is 20 inches and the width is 16.

Answer 2

320 = L * (L - 4)
320 = L^2 -4l
L^2 - 4L - 320
Use quadratic formula

W = (-b+- sqrt(b^2 - 4ac))/2a
W = -20 and 16

The width can’t be negative so width = 20inches