## College Algebra (10th Edition)

$C(15,15)=1$
Using the combination formula, we obtain: $C(n,r)=\frac{n!}{(n-r)!r!}$ $C(15,15)=\frac{15!}{(15-15)!15!}=\frac{15!}{0!15!}=\frac{15!}{15!\cdot1}=1$