Ch3-111 当(X,Y)为离散:v时,Z也离散 Z=Zk=g(x,y,) P(Z==*)=2P(X=X, Y=y, )k=1,2, 当(X,Y)为连续:时, F2(2)=P(Z≤2)=P(g(X,Y)≤z) lI f(r, y)dxdy 其中D.:{(x,y)g(xy)≤2Ch3-111 当( X ,Y )为离散r.v.时, Z 也离散 ( , ) k k k i j Z = z = g x y  = = = = = k k j k i k k g x y z k i j P Z z P X x Y y ( , ) ( ) ( , ) k =1,2,  当( X ,Y )为连续r.v.时， F (z) P(Z z) Z =  = P(g(X,Y)  z)  = Dz f (x, y)dxdy D : {(x, y) | g ( x, y) z} z 其中 