Question

概率论与数理统计,求边缘密度问题

Answer 1

FX(x)=P(X≤x)

=P(X≤x;-∞＜Y＜+∞)

=∫[-∞;+∞]dy∫[-∞,x]f(x,y)dx

fx(x)=dFX(x)/dx=【∫[-∞;+∞]dy∫[-∞,x]f(x,y)dx】′

=∫[-∞;+∞]f(x,y)dy

=∫[-∞;0]f(x,y)dy+∫[0;x]f(x,y)dy+∫[x;+∞]f(x,y)dy

=.