Find the least value of v+6400/v in the domain v>0.

I have no idea....

Whoever gave you this problem clearly expects you to know that a maximum or minimum for a differentiable function occurs where the derivative is 0. If f(v)= v+ (6400/v), then . Set that equal to 0, solve for v, and find f(v) for that vaue of v.

Last edited by mr fantastic; Jun 7th 2009 at 06:59 PM.
Reason: Fixed latex