问题描述： x的平方+xy分之x+3y加xy+y的平方分之y-x分式 1个回答 分类：数学 2014-10-30 问题解答： 我来补答 (x+3y)/(x²+xy) +(y-x)/(xy+y²)=(x+3y)[x(x+y)] -(x-y)/[y(x+y)]=[(x+3y)y -x(x-y)]/[xy(x+y)]=(xy+3y²-x²+xy)/[xy(x+y)]=-(x²-2xy-3y²)/[xy(x+y)]=-(x+y)(x-3y)/[xy(x+y)]=(3y-x)/(xy)=3/x - 1/y 展开全文阅读
