Let f (x) = alnx − 12x2 + BX. (1) when a = 3, B = 12, find the maximum value of F (x); (2) find the solution set of the inequality f '(x) > F (1)

Let f (x) = alnx − 12x2 + BX. (1) when a = 3, B = 12, find the maximum value of F (x); (2) find the solution set of the inequality f '(x) > F (1)

(1) When a = 3, B = 12, f (x) = 3lnx-12x2 + 12x (x > 0) f '(x) = 3x − x + 12 = − (x − 2) (2x + 3) 2x ∵ x > 0. When 0 < x < 2, f' (x) > 0, that is, f (x) increases. When x > 2, f '(x) < 0, that is, f (x) decreases