初一分式求值

题目

初一分式求值
已知1/x-1/y=3,求分式：(2x+3xy-2y)/(x-2xy-y)的值,要过程!过程!

答案

1/x-1/y=3,
(y-x)/xy=3
y-x=3xy
x-y=-3xy
(2x+3xy-2y)/(x-2xy-y)
=[2(x-y)+3xy]/[(x-y)-2xy]
=(-6xy+3xy)/(-3xy-2xy)
=-3xy/(-5xy)
=3/5