Question

A closed box has a square base with side length L feet and height h feet. Given that the volume of the box is 39 cubic feet, express the surface area of the box in terms of L only. Need help please?

Answer 1

`=(2L^2+156/L )ft^2`

Explanation:

Given that the volume of the box `V=39ft^3`

Again `"volume "V= "area of base"xx"height"=L^2xxh`

So `h=V/L^2=39/L^2`

Now surface area of the box
`S=2(L^2+Lxxh+Lxxh)=2(L^2+2xxLxxh)`

`=2(L^2+2xxLxx39/L^2)`

`=(2L^2+156/L )ft^2`