(a+b)3=a3+3a2b+3ab2+b3(a-b)3=a3-3a2b+3ab2-b3a3+b3=(a+b)(a2-ab+b2)a3-b3=(a-b)(a2+ab+b2)
http://baike.baidu.com/view/838760.html?wtp=tt
