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

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

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

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?