初一下分式的加减法1.a-b分之a+2b+b-a分之b-a-b分之2a2.xy分之x²+xy-xy分之z²-xy3.m²+xm分之6m-1-m²+2m分之5m-34.x²+3x分之5x-7-x²+3x分之4x-105.a²-1分之a+a²-1分之3a+1+1-a²

Question

初一下分式的加减法
1.a-b分之a+2b+b-a分之b-a-b分之2a
2.xy分之x² +xy-xy分之z² -xy
3.m² +xm分之6m-1-m² +2m分之5m-3
4.x² +3x分之5x-7-x² +3x分之4x-10
5.a² -1分之a+a² -1分之3a+1+1-a² 分之2a+3

Answer 1

1.a-b分之a+2b+b-a分之b-a-b分之2a
=(a+2b)/(a-b)-b/(a-b)-2a/(a-b)
=(a+2b-b-2a)/(a-b)
=(-a+b)/(a-b)
=-1
2.xy分之x² +xy-xy分之y² -xy
=(x²+xy)/xy-(y²-xy)/xy
=(x²+xy-y²+xy)/xy
=(x²+2xy-y²)/xy
3.m² +2m分之6m-1-m² +2m分之5m-3
=(6m-1)/(m²+2m)-(5m-3)/(m²+2m)
=(6m-1-5m+3)/(m²+2m)
=(m+2)/m(m+2)
=1/m
4.x² +3x分之5x-7-x² +3x分之4x-10
=(5x-7)/(x²+3x)-(4x-10)/(x²+3x)
=(5x-7-4x+10)/x(x+3)
=(x+3)/x(x+3)
=1/x
5.a² -1分之a+a² -1分之3a+1+1-a² 分之2a+3
=a/(a²-1)+(3a+1)/a²-1)-(2a+3)/(a²-1)
=(a+3a+1-2a-3)/(a²-1)
=(2a-2)/(a²-1)
=2/(a-1)/(a-1)(a+1)
=2/(a+1)