Find the dimensions of a rectangle whose perimeter is 42 m and whose area is 104m ^2
Perimeter = 2 (W + L)
42 = 2(W + L)
21 = W + L
21 - W = L
Area = L * W
104 = (21 - W) * W
104 = 21W - W^2
W^2 - 21W + 104 = 0 factor
(W - 13) ( W - 8) = 0
Setting both factors to 0 and solving for W gives us the dimensions
13 and 8
