设随机变量(X,Y)的概率密度为f(x,y)=Be^-(x+y),0

由归一性有：∫(从0积到1)∫(从0积到+∞) B*e^[-(x+y)] dydx = B*∫(从0积到1) e^(-x) dx * ∫(从0积到+∞) e^(-y) dy = B*[1 - e^(-1)]*1 = B*[1 - e^(-1)] = 1所以B = e/(e - 1)x的边缘密度函数fx(x) = ∫(从0积到...