原式=m*m+m*3n+m*3p-2n*m-2n*3n-2n*3p+3p*m+3p*3n+3p*3p
=m^2+3mn+3mp-2mn-6n^2-6np+3mp+6pn+9p^2
=m^2-6n^2+9p^2+mn+6mp
(m^2意思是 m的平方)