已知 1/x-1/y=3 求 2x-3xy-2y / x-2xy-y=?

已知 1/x-1/y=3 求 2x-3xy-2y / x-2xy-y=?
已知 1/x-1/y=3 求 2x-3xy-2y / x-2xy-y=?

已知 1/x-1/y=3 求 2x-3xy-2y / x-2xy-y=?
(2x-3xy-2y)/(x-2xy-y)
=[(2/y)-3-(2/x)]/[(1/y)-2-(1/x) (分子分母同时乘以1/(xy))
=[2(1/x-1/y)-3]/[(1/x-1/y)-2]
∵1/x-1/y=3
∴原式=(6-3)/(3-2)=3

∵1/x-1/y=3
∴y-x=3xy
x-y=-3xy
2x-3xy-2y/x-2xy-y
=[2(x-y)-3xy]/[(x-y)-2xy]
=(-6xy-3xy)/(-3xy-2xy)
=-9xy/(-5xy)
=9/5

应该等于9/5