Please help with the attached question:

)Let 1' have the negative binomial distribution with parameters It and and p, that is, Y is the number of failures observed in order to attain (a predetermined) k successes in a sequence of Bernoulli trials with probability of success p Such a distribution 1s often considered when modeling count data where the variance is larger than the mean (an overdispersed Poisson)- Show that the negative binomial family is an exponential family where the natural par\";- ._