约分下列分式(x-y)/(y-x)³(x²-9)/(6-2x)(x²-1)/(x-x²)

约分下列分式(x-y)/(y-x)³(x²-9)/(6-2x)(x²-1)/(x-x²)
约分下列分式
(x-y)/(y-x)³
(x²-9)/(6-2x)
(x²-1)/(x-x²)

约分下列分式(x-y)/(y-x)³(x²-9)/(6-2x)(x²-1)/(x-x²)
(x-y)/(y-x)³
=-1/(x-y)²
(x²-9)/(6-2x)
=(x+3)(x-3) /[-2(x-3)]= -(x+3)/2
(x²-1)/(x-x²)
=(x+1)(x-1) /[-x(x-1)] =-(x+1)/x

1、-1/(x^2+xy+y^2)
2、-(x+3)/2
3、-(x+1)/x

都是先因式分解，然后约分