The length of a rectangular deck is 5 feet longer than its width, x. The area of the deck is 310 square feet. What equation can be used to determine the width of the deck?

1 Answer
Jul 9, 2017

see explanation

Explanation:

The area of a quadrilateral (which includes rectangles) is lxxw or length times width. The area here is stated to be 310 square feet (ft^2).

We're told that the length is 5 feet longer than the width, and that x represents the width. Thus...

l=5+x
w=x
\thereforelxxw=(5+x)\cdot(x)=310 ft^2


Now you have an algebraic variable question to solve.

  • (5+x)\cdot(x)=310
  • Apply Distributive Property: x(5)+x(x)=310
  • 5x+x^2=310, moving everything to one side gets you a quadratic:
  • x^2+5x-310=0

Solving by Quadratic Formula