A rectangular garden of area 75 ftö is bounded on three sides by a wall costing
$8 per ft and on the fourth by a fence costing $4 per ft. What are the most economical dimensions of the garden?
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
