Find the dimensions using a quadratic equation

Question

The length of a rectangular piece of sheet steel is 4 in longer than five times the width. Find the dimensions if the area of the sheet is 168 sq. in. Solve using a quadratic equation.

Answer 1

L = 4+5W

Area = LxW = (4+5W)x(W) = 5W*2 + 4W = 168

Rewrite in quadratic form as: 5W*2 + 4W - 168 = 0

Use the Quadratic Formula to solve:

where:

a = 5

b = 4

c = -168

Do the math and you have only one solution that makes sense:

W = 5.41

L = 31.05