# Math Help - Joint PGF of two non-independent random variables.

1. ## Joint PGF of two non-independent random variables.

Working through a question, I've obtained the following:

$G_{u}(z) = \frac{1}{2}(1+z^2)$

$G_{v}(z) = \frac{\frac{5}{2}(1+z)}{7-2z}$

I'm now asked to obtain the joint PGF of U and V. These two random variables are not independent; how would I go about finding the joint PGF in this case?

2. you cannot obtain joint dsitributions from marginals without knowing at least one conditional distribution or independence.
That's the study of copulas.