Question

Differentiation problem:

Answer 1

Initially I set h=10r (Since h = diameter x5) then I sub it back into the given equation. Then I solve it using dv/dr but I don't think its the right way to do it.

Tbh I am not clear about how to solve it. Could someone point me in the right direction?

Answer 2

here height= diameter+5 so simply taking it as h=d+5
V=(1/3)*pi * (d/2)^2 * (h)
since V=40, put h =d+5 in the above formula and you will get a quadratic equation in d.
when you get 'd', divide it by 2 to get radius.

Answer 3

I was seeing 5x instead of +5! Stupid mistake. Thanks mate