the height h is 20/x^2
The cost in cents is thus
c = 42x^2 + 26x^2 + 4*10*x(20/x^2)
= 68x^2 + 800/x
A rectangular box is to have a square base and a volume of 20 ft3. The material for the base costs 42¢/ft2, the material for the sides costs 10¢/ft2, and the material for the top costs 26¢/ft2. Letting x denote the length of one side of the base, find a function in the variable x giving the cost (in dollars) of constructing the box.
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