Question

设（X、Y)的概率密度为 f(x、y)=｛1/3（x＋y）,0≤x≤2,0≤y≤1, ｛0,其他

Answer 1

问：设（X、Y)的概率密度为 f(x、y)=｛1/3（x＋y）,0≤x≤2,0≤y≤1, ｛0,其他

答：你好，∫ f(x,y) dy∫ f(x,y) dxfx(x)=(1/3) ∫(0~1) (x+y) dy=(1/3){xy+y^2/2 (y:0~1)}=(1/3)(x+1/2)(0<=x<=2)=0 elsefy(y)=(1/3){x^2/2+yx (x:0~2)}=(1/3)(2+2y)=(2/3)(y+1)(0<=y<=1)=0 else