问题描述: 已知x,y均小于1大于0,试证x+y-xy 1个回答 分类:数学 2014-12-08 问题解答: 我来补答 x+y-xy-1=(x-xy)+(y-1)=x(1-y)-(1-y)=(1-y)(x-1)∵0<x<1,0<y<1∴0<1-y<1,x-1<0∴(1-y)(x-1)<0∴x+y-xy 展开全文阅读