## Intermediate Algebra for College Students (7th Edition)

$21$
Formula to calculate the Binomial Coefficient is: $\displaystyle \binom{n}{k}=\dfrac{n!}{k!(n-k)!}$ Let's see how this formula works: $\displaystyle \binom{7}{2}=\dfrac{7!}{2!(7-2)!}=\dfrac{ 7 \cdot 6 \cdot 5!}{ 2 \cdot 1 \times 5!}=21$