Question

(1+n/m)除以(1-n/m)乘以(m的2次方-n的2次方)

Answer 1

(1+n/m)/(1-n/m)*(m^2-n^2)

=(m+n)/(m-n)*(m+n)*(m-n)

=(m+n)*(m+n)

=m^2+n^2+2mn