当x→1+时x-1→0+;ln(x-1)→-∞
所以,该问题是0*∞型的
令y=x-1,则y→0+
lim(x-1)ln(x-1)
=limylny
=lim[lny/(1/y)]
=lim[(lny)′/(1/y)′]
=lim[(1/y)/(-1/y^2)]
=lim(-y)=0
lim的下面的x→1+ 换成了y→0+
当x→1+时x-1→0+;ln(x-1)→-∞
所以,该问题是0*∞型的
令y=x-1,则y→0+
lim(x-1)ln(x-1)
=limylny
=lim[lny/(1/y)]
=lim[(lny)′/(1/y)′]
=lim[(1/y)/(-1/y^2)]
=lim(-y)=0
lim的下面的x→1+ 换成了y→0+