已知1/x-1/y=2,求x-y-5xy/2x-2y+3xy

来源：学生作业帮编辑：大师作文网作业帮分类：数学作业时间：2024/11/12 09:02:08

通分
1/x-1/y=(y-x)/xy=2
y-x=2xy
所以x-y=-2xy
原式=[(x-y)-5xy]/[2(x-y)+3xy]
=[(-2xy)-5xy]/[2(-2xy)+3xy]
=-7xy/(-xy)
=7

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