9x^4+9x^3y^3-9xy-9y^4
8m^2+6mn+m
2m^3n^3-8m^2n^3大哥。过程呢。啊 还要过程要啊3x^3(3x+3y^3)-3y(3x+3y^3)=9x^4+9x^3y^3-9xy-9y^48m^2-2m+5mn+mn-m=8m^2+6mn+m2mn(4m^2n^2-3mn^2-3m^2n^2-mn^2)=2mn(m^2n^2-4mn^2)=2m^3n^3-8m^2n^3