已知xy分之y-x=3,求x-2xy-y分之3x-5xy-3y的值

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已知xy分之y-x=3,求x-2xy-y分之3x-5xy-3y的值

已知xy分之y-x=3,求x-2xy-y分之3x-5xy-3y的值
已知xy分之y-x=3,求x-2xy-y分之3x-5xy-3y的值

已知xy分之y-x=3,求x-2xy-y分之3x-5xy-3y的值
(y-x)/xy=3
y/xy-x/xy=3
所以1/x-1/y=3
(3x-5xy-3y)/(x-2xy-y)分子分母同时除以xy
原式=(3/y-5-3/x)/(1/y-2-1/x)
=[3(1/y-1/x)-5]/[(1/y-1/x)-2]
=[3*(-3)-5]/(-3-2)
=-14/-5
=14/5

(y-x)/(xy)=3
y-x=3xy
(3x-5xy-3y)/(x-2xy-y)
=[3(x-y)-3xy]/[(x-y)-2xy]
=(-9xy-3xy)/(-3xy-2xy)
=-12/(-5)
=12/5
=2.4