# Thread: using derivatives to solve word problms

1. ## using derivatives to solve word problms

A box with a square base and open top must have a volume of 32,000 cm^3 . Find the dimensions of the box that minimize the amount of material used.

Now I know the general method, I'm just not sure how to set it up. so far I've come up with the equation:
32,000=y*x (y*x means y times x)

I've been trying to think up a second equation to find the dimensions but it's just not coming to me. Any thoughts?

2. Originally Posted by mlckb1
$x^2y = 32000$
surface area , $S = x^2 + 4xy$
get $S$ in terms of a single variable and minimize