随机变量数字特征
来源:学生作业帮 编辑:搜搜做题作业网作业帮 分类:数学作业 时间:2024/07/08 12:47:27
随机变量数字特征
E(X-c)^2=E[(X-EX)+(EX-c)]^2=E[(X-EX)^2]+2E[(X-EX)(EX-c)]+(EX-c)^2
=E[(X-EX)^2]+2[(EX-EX)(EX-c)]+(EX-c)^2
=E[(X-EX)^2]+(EX-c)^2
≥E[(X-EX)^2]=DX
当c=EX时,DX=E(X-c)^2
再问: 谢谢O(∩_∩)O
=E[(X-EX)^2]+2[(EX-EX)(EX-c)]+(EX-c)^2
=E[(X-EX)^2]+(EX-c)^2
≥E[(X-EX)^2]=DX
当c=EX时,DX=E(X-c)^2
再问: 谢谢O(∩_∩)O