How do you find the critical values for f(x) = xsqrt(x-a), where "a" is a constant.  (What is/are the general critical point value(s)?)

I don't do the problem for you, but I give you hints on how to figure it out.  Be sure to first try it yourself, only watching the video if you run into a wall or solve it and want another perspective on how to approach it.