已知 1/x-1/y=5.求(2x+4xy-2y)/(x-3xy-y)
问题描述：
已知 1/x-1/y=5.求(2x+4xy-2y)/(x-3xy-y)
答
1/x-1/y=5
(y-x)/xy=5
y-x=5xy
(2x+4xy-2y)/(x-3xy-y)
=[4xy-2(y-x)]/[-3xy-(y-x)]
=(4xy-10xy)/(-3xy-5xy)
=(-6)/(-8)
=3/4