3. [4] Let f(x) = 2x3 - 15x2 - 144x. Answer the following questions. a) f (x) is increasing on: and f(x) is decreasing on: b) f (x) is concave upward: and f(x) is concave downward: c) f (x) has a local maximum at x = and f (x) has a local minimum at x = d) Does f (x) have an inflection point? If so, give the coordinates of the inflection point. Show work here (must include the sign chart for 1st and 2"d derivative)