(m-2n+p)(m+2n-p)=[m-(2n-p)][m+(2n-p)]=m^2-(2n-p)^2=m^2-4n^2+4np-p^2
（m-2n+p）（m+2n+p）=[(m+p)-2n][(m+p)+2n]=m^2+2mp+p^2-4n^2
（a+b）(a-b)+(a+b)²-2a²=a^2-b^2+a^2+2ab+b^2-2a^2=2ab