f'(X)=3(X2)+3-a ∵在x=1处的切线平行于x轴∴X=1时,f'(X)=0即a=6
∴f'(X)=3(X2)-3; f(x)=x3-3x+b
可求得f'(X)>0时,f'(X)范围是(-∞,-1)∪(1,+∞);f'(X)f'(1),f(4)>f'(4) 可求得b>2 f(0)=b∴f(0)>2
f'(X)=3(X2)+3-a ∵在x=1处的切线平行于x轴∴X=1时,f'(X)=0即a=6
∴f'(X)=3(X2)-3; f(x)=x3-3x+b
可求得f'(X)>0时,f'(X)范围是(-∞,-1)∪(1,+∞);f'(X)f'(1),f(4)>f'(4) 可求得b>2 f(0)=b∴f(0)>2