Find the intervals on which each of the following functions is (a) increasing (b) decreasing.



f’(x)=(12x3-24x2-60x+72)/10


=1.2(x3-2x2-5x+6)


=1.2(x-1)(x-3)(x+2)



Function f(x) is decreasing for x (-∞,-2] [1, 3] and increasing in x (-2,1) (3, ∞)


1