若1/x-1/y=3,则2x+3xy-2y/x-y-2xy的值是多少?
问题描述：
若1/x-1/y=3,则2x+3xy-2y/x-y-2xy的值是多少?
答
1/x-1/y=3
(y-x)/(xy)=3
y-x=3xy
x-y=-3xy
(2x+3xy-2y)/(x-y-2xy)
=[2(x-y)+3xy]/[(x-y)-2xy]
=(-6xy+3xy)/(-3xy-2xy)
=(-3xy)/(-5xy)
=3/5