设X,Y的联合概率密度为f(x,y)=1,0＜x＜1,|y|＜x,其他是0求D(X),D(Y).
<p>问题：设X,Y的联合概率密度为f(x,y)=1,0＜x＜1,|y|＜x,其他是0求D(X),D(Y).<p>答案：↓↓↓<p class="nav-title mt10" style="border-top:1px solid #ccc;padding-top: 10px;">莫鸿强的回答：<div class="content-b">网友采纳 E(x)=∫xdx∫[-x,x]dy=∫2x^2dx=2/3E(y)=∫dx∫[-x,x]ydy=0E(x^2)=∫x^2dx∫[-x,x]dy=∫2x^3dx=1/2E(y^2)=∫dx∫[-x,x]y^2dy=∫2x^3/3dx=1/6D(x)=E(x^2)-^2)=1/18D(y)=1/...
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