已知1/x-1/y=3,求分式(2x-14y-2y)/(x-2xy-y)的值

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已知1/x-1/y=3,求分式(2x-14y-2y)/(x-2xy-y)的值
已知1/x-1/y=3,求分式(2x-14y-2y)/(x-2xy-y)的值

已知1/x-1/y=3,求分式(2x-14y-2y)/(x-2xy-y)的值
依题意:1/x-1/y=3
通分,则(y-x)/xy=3 所以y-x=3xy
(2x-14xy-2y)/(x-2xy-y)
=[2x-14(y-x)/3-2y]/[x-2(y-x)/3-y]
=(20x/3 - 20y/3)/(5x/3 - 5y/3)
=20(x-y)/5(x-y)
=4

是2x-14xy-2y吧?
x-y=-3xy
(2X-14XY-2Y)/(x-2xy-y)
=[2(x-y)-14xy]/[(x-y)-2xy]
=(-6xy-14xy)/(-3xy-2xy)
=20xy/5xy
=4