(a+b)2=a2+2ab+b2 (a+b)3=?
问题描述：
(a+b)2=a2+2ab+b2 (a+b)3=?
答
(a+b)2=a2+2ab+b2
(a+b)3=(a+b)( a2+2ab+b2)
=a3++2a2b+ab2+a2b+2ab2+b3
=a3+3a2b+3ab2+b3