若1/x-1/y=3,则分式3x-xy-3y/x+2xy-y的值为A:2 B:8/5 C:10 D:-10

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若1/x-1/y=3,则分式3x-xy-3y/x+2xy-y的值为A:2 B:8/5 C:10 D:-10
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若1/x-1/y=3,则分式3x-xy-3y/x+2xy-y的值为A:2 B:8/5 C:10 D:-10
若1/x-1/y=3,则分式3x-xy-3y/x+2xy-y的值为
A:2 B:8/5 C:10 D:-10

若1/x-1/y=3,则分式3x-xy-3y/x+2xy-y的值为A:2 B:8/5 C:10 D:-10
是(3x-xy-3y)/(x+2xy-y)的吧?
如果是则 选C
由1 /x -1/ y =3,得y-x=3xy,
∴x-y=-3xy,
∴原式=(3(x-y)-xy)/( (x-y)+2xy) =(-9xy-xy)/( -3xy+2xy) =-10xy /-xy =10
故答案为C.

令x=1/6,则y=1/3,分式的解如下:
3*(1/6)-(1/3)*(1/6)-3*(1/3)/(1/6)+2*(1/3)*(1/6)-(1/3)
=1/2-1/18-2+1/9-1/3
=-9/16

-(10/9)

有条件得到:y-x=3xy,即:x-y=-3xy,带入得到:
所求式子
=3(-xy)-xy/(-3xy+2xy)
=4.