用逐项微分法求随机变量的数学期望与方差

To Get the Digital Expectation and Variance of Random Variance by the Method of Termwise Differentiation

应用高等数学中的逐项微分法来求随机变量的数学期望和方差

Introducing the method of termwise differentiation in high mathematits to get the digital expectationand variance of random variance