二项式定理的证明利用数学归纳法证明二项式定理：证明： （1）当n1时，左边(ab)1ab， 右边ab左边右边，所以等式成立（2）假设当nk时等式成立，即那么，当nk1时，利用组合数旳两个重要性质可得即nk1时等式也成立根据（1）和（2），可知对于任意正整数n，等式都成立一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一一
