Posted by John on .
Consider a right circular cylinder whose total surface area (top, bottom, side) is 300 pi; what must its radius be in order that the volume be as large as possible

Math 
Steve,
2πr^2 + 2πrh = 300
h = (3002πr^2)/2πr
= 150/πr  r
v = πr^2 h = πr^2(150/πr  r)
= 150r  πr^3
dv/dr = 1503πr^2
max v occurs when r=√(50/π)