(a^m+b^m)(a^n+b^n)-2(a^(m+n)+b^(m+n))
=a^(m+n)+a^n*b^m+a^m*b^n+b^(m+n)-2a^(m+n)-2b^(m+n)
=-a^m*a^n-b^m*b^n+a^n*b^m+a^m*b^n
=-a^m(a^n-b^n)+b^m(a^n-b^n)
=-(a^m-b^m)(a^n-b^n)
当a>b时:a^m-b^m>0;a^n-b^n>0,等式
(a^m+b^m)(a^n+b^n)-2(a^(m+n)+b^(m+n))
=a^(m+n)+a^n*b^m+a^m*b^n+b^(m+n)-2a^(m+n)-2b^(m+n)
=-a^m*a^n-b^m*b^n+a^n*b^m+a^m*b^n
=-a^m(a^n-b^n)+b^m(a^n-b^n)
=-(a^m-b^m)(a^n-b^n)
当a>b时:a^m-b^m>0;a^n-b^n>0,等式