[JEE Main 2003] binom n r 1 binom n r 1 2 binom nr equals
$\binom n{r+1}+\binom n{r-1}+2\binom nr$ equals
(a) $\binom{n+1}{r+1}$
(b) $\binom{n+2}r$
(c) $\binom{n+2}{r+1}$
(d) $\binom{n+1}r$
1 Answer
VAVidaara Admin
✓ Vidaara Team
✓ Accepted
· 2d ago
▲ 0
Correct answer: (c) $\binom{n+2}{r+1}$
$(\binom n{r+1}+\binom nr)+(\binom nr+\binom n{r-1})=\binom{n+1}{r+1}+\binom{n+1}r=\binom{n+2}{r+1}$.
JEE Main 2003 · Permutations and Combinations — verified solution by the Vidaara Team.
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