Find the marginals and show that their product != f(x,y).
Do you know how to find the marginal distributions?
...You could also simply use a factorization argument.
If the random variables X and Y have the joint pdf:
f (x, y)= { 2e^-x-y for 0<x<y, 0<y<∞
0, elsewhere
Show that X and Y are dependent.
Please help me...