通分1/a+b,1/a^2-b^2,2/a^-ab

问题描述:

通分1/a+b,1/a^2-b^2,2/a^-ab

1/(a+b)=a(a-b)/[a(a+b)(a-b)]=a(a-b)/[a(a²-b²)]=(a²-ab)/[a(a²-b²)]1/(a²-b²)=a/[a(a²-b²)]2/(a²-ab)=2/[a(a-b)]=2(a+b)/[a(a+b)(a-b)]=2(a+b)/[a(a²-b...