1/(m2-m)+(m-5)/(2m2-2) y/(x+y)+xy/(y2-x2)(a+5)/(5a-20)+5/(a2-9a+20)1/(x-3)-6/(x2-9)-(x-1)/(6+2x)注：2在字母后面的是平方.

1/(m2-m)+(m-5)/(2m2-2) y/(x+y)+xy/(y2-x2)(a+5)/(5a-20)+5/(a2-9a+20)1/(x-3)-6/(x2-9)-(x-1)/(6+2x)注：2在字母后面的是平方.
1/(m2-m)+(m-5)/(2m2-2)
y/(x+y)+xy/(y2-x2)
(a+5)/(5a-20)+5/(a2-9a+20)
1/(x-3)-6/(x2-9)-(x-1)/(6+2x)
注：2在字母后面的是平方.

1/(m2-m)+(m-5)/(2m2-2) y/(x+y)+xy/(y2-x2)(a+5)/(5a-20)+5/(a2-9a+20)1/(x-3)-6/(x2-9)-(x-1)/(6+2x)注：2在字母后面的是平方.
1,=1/m(m-1)+(m-5)/2(m+1)(m-1)
=2(m+1)/2(m+1)(m-1)+(m2-5m)/2(m+1)(m-1)
=(2m+2+m2-5m)/2(m+1)(m-1)
=(m2-3m+2)/2(m+1)(m-1)
=(m-2)(m-1)/2(m+1)(m-1)
=(m-2)/2(m+1)
2,=y/(x+y)+xy/(y-x)(y+x)
=(y2-xy+xy)/(y-x)(y+x)
=y2/(y-x)(y+x)
3,=(a+5)/5(a-4)+5/(a-4)(a-5)
=(a2-25)/5(a-4)(a-5)+25/5(a-4)(a-5)
=a2/5(a-4)(a-5)
4,=(2x+6)-12-(x2-4x+3)/2(x+3)(x-3)
=(x-3)(x-3)/2(x+3)(x-3)
=(x-3)/2(x+3)

2. -Y2/（x2-y2)