How to solve please?

A box with a square base and open top must have a volume of 500000 cm . We wish to find the dimensions of the box that minimize the amount of material used. First, find a formula for the surface area of the box in terms of only a, the length of one side of the square base. [Hint: use the volume formula to express the height of the box in terms of x.] Simplify your formula as much as possible. A(x) Next, find the derivative, A'(x). A'(x) Now, calculate when the derivative equals zero, that is, when A'(a) = 0. [Hint: multiply both sides by a2.] A'(x) = 0 when r : We next have to make sure that this value of a gives a minimum value for the surface area. Let's use the second derivative test. Find A"(x). A"(I ) Evaluate A"(x) at the r-value you gave above. NOTE: Since your last answer is positive, this means that the graph of A() is concave up around that value, so the zero of A'(I) must indicate a local minimum for A(x). (Your boss is happy now.)