2. (7.5分) 设(x,y)的概率密度为 f(x,y)=}(x+y)/3,&0le xle 2,0le yle 1,0,&其他. 则EX=iintlimits_(R)xf(x,y)dxdy=int_(0)^2int_(0)^1x(x+y)/3dxdy. A 对 B 错A. 对B. 错

2. (7.5分) 设(x,y)的概率密度为 $f(x,y)=\begin{cases}(x+y)/3,&0\le x\le 2,0\le y\le 1,\\0,&其他.\end{cases}$ 则$EX=\iint\limits_{R}xf(x,y)dxdy=\int_{0}^{2}\int_{0}^{1}x(x+y)/3dxdy$. A 对 B 错

A. 对

B. 错