Thread: application of differentiation question

Hey

I am having trouble with this question.

Consider a cylindrical can which has some fixed volume V. If r is the radius of the circular cross-section and h is the height, show that the values of r and h which will minimise the surface area are related by h = 2r.

Now I have Surface Area (SA) =

Then i replace the h in that equation with h in terms of r.



But then how do I get rid of the V?

is a constant...