已知x分之1-y分之1=3,求x-2xy-y分之5 - 知识问答

已知x分之1-y分之1=3,求x-2xy-y分之5x+3xy-5y

1个回答

1/x-1/y=3
(y-x)/xy=3
y-x=3xy
x-y=-3xy
所以原式=[5(x-y)+3xy]/[(x-y)-2xy]
=(-15xy+3xy)/(-3xy-2xy)
=(-12xy)/(-5xy)
=12/5

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