/sci/ - Science & Math

Need help with question 2a:
"Show that p(subzero) = 1 - p"

I get that the probability function given is like an additive series where you substitute in values k to infinity and all of that is equal to 1 (total probability), but I have no idea how you go from knowing that to finding what the question is asking for.

I even looked at the answers and he expanded out the first few entries of the additive series:
p(sub0) x p^0 + p(sub0) x p^1 + p(sub0) x p^2 + ... = p(sub0) / 1 - p = 1

How.The.Fuck did he manage to make all of the additive series equal to p(naught) / 1 - p ?????

It's doing my head in, pls help