f'(x)=cosx-1,x屬于(0,Pai),那么有-1
(2)f'(x)=6x^2+6x-24=6(x^2+x-4)>0
x^2+x>4
(x+1/2)^2>17/4
x>-1/2+根號(hào)17/2,或X<-1/2-根號(hào)17/2
故單調(diào)增區(qū)間是(-1/2+根號(hào)17/2,+OO)和(-OO,-1/2-根號(hào)17/2)
同理有f'(x)<0可得單調(diào)減區(qū)間是(-1/2-根號(hào)17/2,-1/2+根號(hào)17/2)