Question

【2/(m+n)^3】*【(1/m)+(1/n)】+【1/(m^2+2mn+n^2)】*【(1/m^2)+(1/n^2)

Answer 1

原式=[2//(m+n)^3][(m+n)/mn]+[1/(m+n)^2][(m^2+n^2)/m^2n^2]

=2/[mn(m+n)^2]+(m^2+n^2)/[m^2n^2(m+n)^2]

=(2mn+m^2+n^2)/[m^2n^2(m+n)^2]

=(m+n)^2/[m^2n^2(m+n)^2]

=1/m^2n^2