Let f(x)=1/5x^5 + 3/2x^4 - 23x^3 + 23x^2 + 120x -56
(a) the critical points of f (if any),
(b) the open intervals on which the function is increasing or decreasing, and
(c) the location of all relative extremes (if any).
I'm kind of familiar with doing these but I have no idea on this...