Given the function f(x) =x23(6 -x)143. Find the following: (a) the intervals where f(x) is increasing and where f(x) is decreasing; (b) the relative extrema of f(x), if any; (c) the intervals where f(x) is concave upward and where f(x) is concave downward; and (d) all the inflection point(s) of f(x), if any