我们知道以分布列为基础的离散型随机变量ξ的期望与ξ2的期望具有不等的关系Eξ2≥(Eξ)2,就是这个不等式,把随机数学的概率与确定性数学的不等式有机结合起来,显示出数学的统一性,体现了数学的和谐美.这样一个平凡的认识指引了一条新的解题方向.下面笔者就以本刊《数学问题解 We know that the expectation of the distribution-based discrete random variable ξ has a different relationship with the expectation of ξ2. Eξ2≥ (Eξ) 2 is the inequality. Combining the probability of stochastic mathematics with the inequality of deterministic mathematics, Showing the unity of mathematics, reflects the harmonious beauty of mathematics.An ordinary understanding of this guide a new direction of the problem.The author follows the publication of "mathematical problem solution