Question

有点难度的初一数学应用题

Answer 1

S1=(m^2-n^2)^2=m^4-2m^2n^2+n^4

S2=(2mn)^2=4m^2n^2

S3=(m^2+n^2)^2=m^4+2m^2n^2+n^4

故有S3=S1+S2