For $2 \le r \le n,\left( {\begin{array}{*{20}{c}}n\\r\end{array}} \right) + 2\,\left( \begin{array}{l}\,\,n\\r - 1\end{array} \right)$ $ + \left( {\begin{array}{*{20}{c}}n\\{r - 2}\end{array}} \right)$ is equal to
For $2 \le r \le n,\left( {\begin{array}{*{20}{c}}n\\r\end{array}} \right) + 2\,\left( \begin{array}{l}\,\,n\\r - 1\end{array} \right)$ $ + \left( {\begin{array}{*{20}{c}}n\\{r - 2}\end{array}} \right)$ is equal to
- [IIT 2000]
- A
$\left( {\begin{array}{*{20}{c}}{n + 1}\\{r - 1}\end{array}} \right)$
- B
$2\,\left( {\begin{array}{*{20}{c}}{n + 1}\\{r + 1}\end{array}} \right)$
- C
$2\,\left( {\begin{array}{*{20}{c}}{n + 2}\\r\end{array}} \right)$
- D
$\left( {\begin{array}{*{20}{c}}{n + 2}\\r\end{array}} \right)$
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