So if x = length of one side of the square base, and the volume is 10 cu.ft., then,

Volume = (x^2)*y = 10

and y = 10/(x^2) ft.

a) A = Area of base + area of 4 sides

A = x^2 +4(x)(y)

A = x^2 +4x[10/(x^2)] ----you got this far.

A = x^2 +40/x

In function form,

A(x) = x^2 +40/x ----------answer.

b) If x=1, what is A(1)?

A(1) = 1^2 +40/1 = 1 +40 = 41 sq.ft. --------answer.

c) If x=2, what is A(2)?

A(2) = 2^2 +40/2 = 4 +20 = 24 sq.ft. --------answer.

d) Graph A(x) = x^2 +40/x, and find the minimum A.

I don't know how to graph this on calculators or in computers. I can do it by getting mamy points or ordered pairs.

It looks like it is an skewed hyperbola, with branches in the 1rst and 3rd quadrants.

In my rough sketch, minimum A appears to be between x=2 and x=3.

That's as far as I can go.