...的概率密度函数为xe^-y ,0<x<y 其他为0 求(X,Y)分布函数F(X,Y...答:f(x,y)=xe^(-y),0<x<y当0<x<y时,F(x,y)=P(X<=x,Y<=y)=∫∫xe^(-y)dxdy=∫(0,x) xdx∫(x,y) e^(-y)dy=1-(x+1)e^(-x)-x^2/2*e^(-y)当0<y<x时,F(x,y)=P(X<=x,Y<=y)=∫∫xe^(-y)dxdy=∫(0,y) xdx∫(x,y) e^(-y)dy=1-(y+1)e^(-y)-y^2...