If n and r are two positive integers such that n ge r, then ^n{C_{r - 1}} + {,^n}{Cᵣ} =

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6.Permutation and Combination

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If $n$ and $r$ are two positive integers such that $n \ge r,$ then $^n{C_{r - 1}}$$ + {\,^n}{C_r} = $

A

$^n{C_{n - r}}$

B

$^n{C_r}$

C

$^{n - 1}{C_r}$

D

$^{n + 1}{C_r}$

Solution

(d) $^n{C_{r – 1}}\, + {\,^n}{C_r}\, = {\,^{n + 1}}{C_r}$ is a standard formula.

Standard 11

Mathematics

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