lim(x^2+2x-3)/(x^2-1) (x->1)

lim(x^2+2x-3)/(x^2-1)

=lim(x+3)(x -1)/(x-1)(x+1)

=lim(x+3)/(x+1)

=lim(x+1+2)/(x+1)

==lim(1+2/(x+1))

=1

你是几年级的？这题如果用大学的数学分析里的克莱姆法则运算是很简单的啊！
lim(x^2+2x-3)/(x^2-1) =lim（2x+2）/2x=2

分子分母分别求导