## College Algebra 7th Edition

$\displaystyle \left(\begin{array}{l}n\\1\end{array}\right)=\frac{n!}{1!(n-1)!}=\frac{n(n-1)!}{1*(n-1)!}=\frac{n}{1}=n$ $\displaystyle \left(\begin{array}{l} n\\n-1\end{array}\right)=\frac{n!}{(n-1)!1!}=\frac{n(n-1)!}{(n-1)!*1}=\frac{n}{1}=n$ Thus we have shown that: $\left(\begin{array}{l}n\\1\end{array}\right)=\left(\begin{array}{l}n\\n-1\end{array}\right)=n$