计算lim(2/(x^2-1)-1/(x-1))
问题描述：
计算lim(2/(x^2-1)-1/(x-1))
答
看题应该是x趋于1
先通分2/(x^2-1)-1/(x-1)=2/(x^2-1)-(x+1)/(x^2-1)=(1-x)/(x^2-1)=-1/(x+1)
极限=-1/(1+1)=-1/2