Question

A rectangle is 6 centimeters longer than is wide and has an area of 280 square centimeters if l represent the length,in centimeters of the rectangle solving which of the following formulas will give the correct value for l?

Answer 1

A = L * W
W = L - 6

280 = L(L - 6) or 280 = L^2 - 6L

Answer 2

l = w+6
a = 280 = w*(w+6)
280 = w^2+ 6w.
0 = w^2 + 6w - 280
w^2 + 20w - 14w - 280
(w^2 + 20w) - (14w-280)
w(w + 20) - 14(w + 20)
0 = w - 14 OR 0 = w + 20
-20=w OR 14=w
14 must be the answer, you cannot have negative width. Ergo, length = 20.
Width + 6, 14 + 6, 20 = length