Question

通分1/a+b,1/a^2-b^2,2/a^-ab

Answer 1

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-b²)]