**negative binomial (r,p) distribution**. Show that the consecutive odds ratio are

P(k)/P(k-1) = (r + k -1)*q/k (k=1,2,3, etc)

**<-- Prove**

Isn't P(k) = (r + k -1

k - 1) * p^k * q^r

Isn't P(k-1) = (r + k -2

k -2) * p^k-1 * q^r

I've looked in my textbook, and the examples seem to say the same thing, however, the proof is just not adding up.