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Permutations and Combinations question

2003 · Shift 0 · Q108

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PYQ Library
JEE Main
Mathematics
Permutations and Combinations
2003 · Shift 0 · Q108

Permutations and Combinations question

2003 · Shift 0 · Q108

JEE MainMathematicsPermutations and CombinationsMCQ+4 / −1

If

{}^n{C_r}

denotes the number of combination of n things taken r at a time, then the expression

\,{}^n{C_{r + 1}} + {}^n{C_{r - 1}} + 2\, \times \,{}^n{C_r}

equals

A
$\,{}^{n + 1}{C_{r + 1}}$
B
${}^{n + 2}{C_r}$
C
${}^{n + 2}{C_{r + 1}}$
D
$\,{}^{n + 1}{C_r}$

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