limx趋近于1 sin(1-x^2)/1-x
问题描述：
limx趋近于1 sin(1-x^2)/1-x
答
limsin(1-x^2)/(1-x)
=lim[sin(1-x^2)/(1-x^2)]*lim(1+x)
=2
答
=limx趋近于1cos(1-x^2)*(-2x)/(-1)
=cos0*(-2)/(-1)
=1*(-2)/(-1)
=2
所以0/0型,分子分母分别求导再数来计算