问题描述: 若1/x -1/y =3,求(2x+3xy-2y)/(x-y-2xy) 1个回答 分类:数学 2014-09-29 问题解答: 我来补答 />1/x -1/y =3y-x/xy=3y-x=3xyx-y=-3xy所以(2x+3xy-2y)/(x-y-2xy)=[2(x-y)+3xy]/(x-y-2xy)=[2(-3xy)+3xy]/(-3xy-2xy)=-3xy/-5xy=3/5答:(2x+3xy-2y)/(x-y-2xy)值为3/5. 展开全文阅读