Question

Collin is building a deck on the back of his house. He has enough lumber for the deck to be 144 square feet. The length should be 10 feet more than its width.
What should the dimensions of the deck be?

Answer 1

Width = x
length = x+10

Area of deck = 144 square feet

Area = length * width

144 = x(x+10)

Solving for x in a quadratic:

x²+10x = 144
x²+10x-144 = 0

Factor:
(x+18)(x-8) = 0

Solving for x:
x = 8, x = -18

Dimensions cannot be negative, therefore x = 8, only.

Length = x + 10
Length = 18

Width = 8