如果1\x-1\y=2,那么3x+5xy-3y\x-xy-y等于多少
问题描述：
如果1\x-1\y=2,那么3x+5xy-3y\x-xy-y等于多少
这是初二的数学题分式那一张的,有知道的请帮帮我,
答
1/x-1/y=2
(y-x)/xy=2
y-x=2xy
(3x+5xy-3y)/(x-xy-y)
=[5xy-3(y-x)]/[-xy-(y-x)]
=(5xy-6xy)/(-xy-2xy)
=-xy/-3xy
=1/3