问题描述: -y - y/1-y +1 1个回答 分类:数学 2014-11-01 问题解答: 我来补答 原式=[-y(y-1)-y+(1-y)]/(1-y)=(-y²+y-y+1-y)/(1-y)=(-y²-y+1)/(1-y) 展开全文阅读