Question

V=((1/3)(pi)(r^2)(h))(3r-h) solve for h

Answer 1

you have thought it in this way ?
pi*r^2 *h*(3r-h)
V = -----------------
3

- so than this is right will get for h :

3V = pi*r^2*h*(3r -h)

3V = 3pi*r^3*h - pi*r^2*h^2

pi*r^2*h^2 -3pi*r^3*h +3V = 0 - so in this case than you see you have got a
quadratic equation in ,,h" - what you can solving exactly like a quadratic equation with unknown x using discriminant

- hope this will help you