P(XY=0)=1
â´P(XYâ 0)=0
â´P(X=-1ï¼Y=-1)
=P(X=-1ï¼Y=1)
=P(X=1ï¼Y=-1)
=P(X=1ï¼Y=1)
=0
âµP(X=-1ï¼Yâ 0)=0
â´P(X=-1ï¼Y=0)=P(X=-1)=1/12
åçï¼
P(X=1ï¼Y=0)=P(X=1)=1/12
â´P(X=0ï¼Y=0)
=P(Y=0)-P(X=-1ï¼Y=0)-P(X=1ï¼Y=0)
=1/3-1/12-1/12
=1/6
â´P(X=Y)
=P(X=-1ï¼Y=-1)+P(X=0ï¼Y=0)+P(X=1ï¼Y=1)
=0+1/6+0
=1/6
追é®
追çP(X=-1)
=P(X=-1ï¼Y=0)+P(X=-1ï¼Yâ 0)