Question

导数简答题f(x)=x^3-（3/2）*(a+1)X^2+3ax+1,若函数f(x)在区间(1,4)内单调递减,求a的取

Answer 1

f'(x)=3(x^2-(a+1)x+a)=3(x-1)(x-a)

在(1,4)内,x-1>0,f'(x)