Let f(x)=1/5x^5 + 3/2x^4 - 23x^3 + 23x^2 + 120x -56

Find :

(a) the critical points off(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 one. The polynomial is huge. Ah!