# Math Help - Independent Random Variable (exponential function)

1. ## Independent Random Variable (exponential function)

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.

2. 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.

3. Yes, i know marginals, but i have a problem that i do not know integrals' lower limit and upper limit.

4. Originally Posted by atalay
Yes, i know marginals, but i have a problem that i do not know integrals' lower limit and upper limit.
$\int_0^y$ and $\int_0^{\infty}...$

5. i am thinking correctly but i do not trust me.

thank you.