已知1/x-1/y=3,求(2x-14xy-2y)/(x-2xy-y)

已知1/x-1/y=3,求(2x-14xy-2y)/(x-2xy-y)
已知1/x-1/y=3,求(2x-14xy-2y)/(x-2xy-y)

已知1/x-1/y=3,求(2x-14xy-2y)/(x-2xy-y)
1/x-1/y=3
通分
(y-x)/xy=3
y-x=3xy
x-y=-3xy
原式=[2(x-y)-14xy]/[(x-y)-2xy]
=[2(-3xy)-14xy]/[(-3xy)-2xy]
=-20xy/(-5xy)
=4

x-y=-3xy
(2x-14xy-2y)/(x-2xy-y)=4

(2x-14xy-2y)/(x-2xy-y)
=（2/y-14-2/x）/(1/y-2-1/x) 即分母分子同时除以xy
=(-6-14)/(-3-2) 即将1/x-1/y=3代入
=4

(2x-14xy-2y)/(x-2xy-y)
=（2/y-2/x-14）/(1/y-1/x-2)
=(-3*2-14)/(-3-2)
=(-20)/(-5)
=4