A box with a rectangular base and top must have a volume of 9m^3. The length of the base is three times the width material for the base costs
$5 per square meter. Material for the sides costs
$4 per square meter. Material for the top costs
$3 per square meter. Find the dimension of the box the minimize the cost.
I understand how to solve for an open-top box. The lid is throwing me for a loop. I believe that you can describe the box with equation f(x)=24x^2+(96/x) but am unsure.