# Exercise C.4.3

Show that $b(k;n,p) = b(n-k;n,q)$, where $q = 1 - p$.

$$b(k;n,p) = \binom{n}{k} p^k q^{n-k} = \binom{n}{n-k} p^k q^{n-k} = \binom{n}{n-k} q^{n-k} p^k = b(n-k;n,q)$$