m^2=n+2 (m^2-n=2)
n^2=m+2 (n^2-m=2)
相减得m^2-n^2=n-m
变换得(m-n)(m+n+1)=0,因m不等于n,m+n+1=0,m+n=-1
m^3-2mn+n^3=m(m^2-n)+n(n^2-m)
=2m+2n
=-2
m^2=n+2 (m^2-n=2)
n^2=m+2 (n^2-m=2)
相减得m^2-n^2=n-m
变换得(m-n)(m+n+1)=0,因m不等于n,m+n+1=0,m+n=-1
m^3-2mn+n^3=m(m^2-n)+n(n^2-m)
=2m+2n
=-2