新课标选修2-3的各种版本教材及配套《教师用书》中,均不同程度涉及超几何分布、二项分布的期望与方差公式,其中人教A版教材的配套《教师用书》(文[1])给出了二项分布的期望与方差公式的证明,文[2]作为其补充给出了超几何分布的期望与方差公式及其证明.但这些证法,除文[1]的二? The new curriculum elective 2-3 various versions of textbooks and supporting “teacher’s book”, are involved in varying degrees of hypergeometric distribution, binomial distribution of expectations and variance formula, in which people teach A version of teaching materials supporting “teacher’s book” ( [1] gives the proof of expectation and variance formula of binomial distribution, and the supplement of [2] gives the expectation and variance formula of hypergeometric distribution and its proof. However, ] Two?