问题标题:
【已知x的-1次方+y的-1次方=5,求分式(2x-xy+2y)/(x+2xy+y)的值.】
问题描述:

已知x的-1次方+y的-1次方=5,求分式(2x-xy+2y)/(x+2xy+y)的值.

邵达友回答:
  1/x+1/y=5   x+y=5xy   (2x-xy+2y)/(x+2xy+y)   =[2(x+y)-xy]/[(x+y)+2xy]   =9xy/7xy   =9/7
郭晓俐回答:
  9xy/7xy是怎么得出来的?
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