m^2-2mn+n^2=?2a^3+8a^2b+8ab^2=?a^2(x-y)+b^2(y-x)=?

问题描述:

m^2-2mn+n^2=?
2a^3+8a^2b+8ab^2=?
a^2(x-y)+b^2(y-x)=?