问题描述： 求几道数学题啦, 1个回答 分类：数学 2014-12-13 问题解答： 我来补答 21.原式＝2/(a-1)-(a+1)/(a-1)=[2-a-1]/(a-1)=-(a-1)/(a-1)=-122.原式＝[x²-2x+1]/(x+1) *(x²-1)/[x²-2x+1]=(x²-1)/(x+1)=x-123.(1)原式＝2-1+4=5(2)原式＝(a²-1)/a*a/(a-1)²=(a+1)(a-1)/(a-1)²=(a+1)/(a-1)=1-1/(a-1) 展开全文阅读
