1. The problem statement, all variables and given/known data Suppose X is a discrete random variable whose probability generating function is G(z) = z^2 * exp(4z-4) 2. Relevant equations No idea 3. The attempt at a solution I'm thinking that due to the exponent on the z term, that the exp(4z-4) would be the P[X=3] = exp(4z-4), but i'm not even sure of this. I honestly have no idea where to even start on a problem like this. Any sort of guidance would be great.