Let's divide the question into the left and right side: The left side: 3x^3 + 6x^2 Take out the greatest common factor (3x^2) 3x^2(x+2)
Now the right side: x+2 Take out greatest common factor (1) 1(x+2)
Notice how each side has a parenthesis of (x + 2); this is good. We combine the matching elements into one, and take the greatest common factors we pulled and make them into a group. As shown:
(3x^2 +1) is the two greatest common factors we pulled.
(x+2) is the common parenthesis. Now combine them for your answer:
A = L * W = 75 so L = 75/W Cost = 4W + 8(2L + W) = 4W + 16L + 8W = 12W + 16L = 12W + 1200/W C' = (12(W^2 - 100))/(W^2) = (12(W-10)(W+10))/(W^2) so W = 10 then L = 7.5