f(x)=ln [(x-1)(x-2)(x-3)]
= ln(x-1)+ln(x-2)+ln(x-3)
f'(x)=1/(x-1)+1/(x-2)+1/(x-3)
f''(x)=- [1/(x-1)^2+1/(x-2)^2+1/(x-3)^2] < 0
根据拐点的条件,函数 f(x)=ln [(x-1)(x-2)(x-3)] 没有拐点.即拐点的个数为零.
//:拐点条件:(1) f''(x0)=0 (2)在x0两侧f''(x)变号.
f(x)=ln [(x-1)(x-2)(x-3)]
= ln(x-1)+ln(x-2)+ln(x-3)
f'(x)=1/(x-1)+1/(x-2)+1/(x-3)
f''(x)=- [1/(x-1)^2+1/(x-2)^2+1/(x-3)^2] < 0
根据拐点的条件,函数 f(x)=ln [(x-1)(x-2)(x-3)] 没有拐点.即拐点的个数为零.
//:拐点条件:(1) f''(x0)=0 (2)在x0两侧f''(x)变号.