约分:(x²-y²-9-2xy)/(x²-y²+6x+9)已知(1)/(x) - (1)/(y)=2,求(3x+xy-3y)/(y-xy-x)的值

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约分:(x²-y²-9-2xy)/(x²-y²+6x+9)已知(1)/(x) - (1)/(y)=2,求(3x+xy-3y)/(y-xy-x)的值

约分:(x²-y²-9-2xy)/(x²-y²+6x+9)已知(1)/(x) - (1)/(y)=2,求(3x+xy-3y)/(y-xy-x)的值
约分:
(x²-y²-9-2xy)/(x²-y²+6x+9)
已知(1)/(x) - (1)/(y)=2,求(3x+xy-3y)/(y-xy-x)的值

约分:(x²-y²-9-2xy)/(x²-y²+6x+9)已知(1)/(x) - (1)/(y)=2,求(3x+xy-3y)/(y-xy-x)的值
(x²-y²-9-2xy)/(x²-y²+6x+9)
错了
(x²+y²-9-2xy)/(x²-y²+6x+9)
=[(x-y)²-9]/[(x+3)²-y²]
=(x-y+3)(x-y-3)/[(x+y-3)(x-y-3)]
=(x-y+3)/(x+y-3)
已知(1)/(x) - (1)/(y)=2,求(3x+xy-3y)/(y-xy-x)的值
1/x-1/y=(y-x)/xy=2
y-x=2xy
x-y=-2xy
原式=[3(x-y)+xy]/[(y-x)-xy]
=(-6xy+xy)/(2xy-xy)
=-5xy/xy
=-5

分子=(X-Y-3)(X-Y+3)
分母=(X+3-Y)(X+3+Y)
分式=(X-Y-3)/(X+Y+3)
根据已知推出Y-X=2XY
分子=-6XY+XY=-5XY
分母=2XY-XY=XY
分式=-5