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


f(x)=-2x3+3x2+12x+6


f’(x)=-6x2+6x+12


f’(x)=-6(x2-x-2)


=-6(x-2)(x+1)



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


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