已知m平方=n+2,n平方=m+2（m不等于n）,求m3处方-2mn+n3次方

m^2=n+2,n^2=m+2
则m^2-n^2=n-m
(m+n)(m-n)=n-m
(m+n+1)(m-n)=0
m不等于n
所以m+n=-1
m^3-2mn+n^3
=mm^2-2mn+nn^2
=m(n+2)-2mn+n(m+2)
=mn+2m-2mn+mn+2n
=2(m+n)
=2*(-1)
=-2