SOLUTION: A closed rectangular box is to be constructed with a square base. The material for the top costs $2 per square foot whereas the material for the remaining sides costs $1 per square

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Question 760994: A closed rectangular box is to be constructed with a square base. The material for the top costs $2 per square foot whereas the material for the remaining sides costs $1 per square foot. If the total cost to construct each box is $36, express the volume of the box in terms of the width of the base.
Answer by josgarithmetic(39618) About Me  (Show Source):
You can put this solution on YOUR website!
The square bottom and top have a side length, w. The rectangular box is height h. Using w and h, the volume of the box is this:
v=h%2Aw%5E2

The volume will also depend on the cost of the six sides making the box.
Top: +w%5E2%2A2 dollars
Bottom: w%5E2%2A1 dollar
One side: h%2Aw%2A1
Cost of the box: 2w%5E2%2Bw%5E2%2B4hw=36______see the factor 4 for the four sides.

We want v as a function of w. We can get this solving the cost equation for h.
4hw=36-2w%5E2-w%5E2
h=36%2F%284w%29-3w%5E2%2F%284w%29
h=9%2Fw-%283%2F4%29w______________Next, substitute this for h in the volume equation, v.

v=%289%2Fw-%283%2F4%29w%29w%5E2
highlight%28v=9w-%283%2F4%29w%5E3%29