Question

化简1/a-b-1/-a-b+1/a+b-1/b-a的结果是

Answer 1

1/(a-b)-1/(-a-b)+1/(a+b)-1/(b-a)

=1/(a-b)+1/(a+b)+1/(a+b)+1/(a-b)

=2/(a-b)+2/(a+b)

=2*(1/(a-b)+1/(a+b))

=2*(a+b+a-b)/(a^2-b^2)

=2*2*a/(a^2-b^2)

=(4*a)/(a^2-b^2)