文[1]给出了六种证明不等式的特殊方法.这里再给出四种,以解决一些不等式的证明问题.1　利用二项式定理证明对于有些不等式,可根据其结构特点,联想或构造二项式模型,利用二项式定理来证.例1　(第2 1届全苏数学竞赛)求证:对于任意的正整数n ,不等式(2n + 1) n ≥(2n) n + (2n - [1] gives six special methods for inequality inequalities. Here, four more are given to solve the problem of some inequalities. 1 The use of binomial theorem proves that for some inequalities, it can be associated or constructed according to its structural characteristics. The binomial model, using the binomial theorem to prove. Example 1 (the 1st all-Su-training math contest) Prove that for any positive integer n, the inequality (2n + 1) n ≥ (2n) n + (2n -