Crit points, extreme values, and basic algebra

Consider the function g(x) = x^2sqrt(5-x)

a)find the intervals on which the function is increasing and decreasing.

I'm stuck at basic algebra here and not sure why. This is what I've got.

g'(x) = 2x*sqrt(5-x) - ((x^2)/(2sqrt(5-x)))

Then I set = 0 and solve for x...

2x*sqrt(5-x) - ((x^2)/(2sqrt(5-x))) = 0

(x^2)/(2sqrt(5-x)) = (2x*sqrt(5-x))

x^2 = (2x*sqrt(5-x))/(2sqrt(5-x))

now, I'm trying to simplify by cancelation but can't remember if I can cancel out the two sqrts or the 2's or both?

Thanks!