A rectangular box is to have a square base and a volume of 70 ft^3. The material for the base costs 26c/ft^2, the material for the sides costs 104c/ft^2, and the material for the top costs 21c/ft^2. 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:
f(x)