Answer
$21$
Work Step by Step
Binomial Coefficient can be defined as:
$\displaystyle \binom{n}{k}=\dfrac{n!}{k!(n-k)!}$
Need to apply the formula to get the Binomial Coefficients.
Here, $n=7,k=2$
Therefore,
$\displaystyle \binom{7}{2}=\dfrac{7!}{2!(7-2)!}$
$=\dfrac{ 7 \cdot 6 \cdot 5!}{ (2 \cdot 1 )(5!)}$ $\bf{(Simplify)}$
$=21$
