The length of a rectangle is 6 centimeters more than its width. The area is 216 square centimeters. What are the dimensions?

18

Step-by-step explanation:

216 divided by 6 = 36

36 divided by 2 = 18

l = 6 + w

A = l * w = 216 cm²

(6 + w) ·w = 216

6w + w² = 216

w² + 6w - 216 = 0

w² + 18w - 12w = 0

w (w + 18) - 12 (w + 18) = 0

(w - 12) (w + 18) = 0

w - 12 = 0 = > w = 12 cm

w + 8 = 0 = > w = - 18 ∉ N

w = 12 cm

l = 12 cm + 6cm

l = 18 cm