Permutations And Combinations Question 51
Question: For $ 2\le r\le n,( \begin{matrix} n \\ r \\ \end{matrix} )+2( \begin{aligned} & n \\ & r-1 \\ \end{aligned} ) $ $ +( \begin{matrix} n \\ r-2 \\ \end{matrix} ) $ is equal to [IIT Screening 2000; Pb. CET 2000]
Options:
A) $ ( \begin{matrix} n+1 \\ r-1 \\ \end{matrix} ) $
B) $ 2( \begin{matrix} n+1 \\ r+1 \\ \end{matrix} ) $
C) $ 2( \begin{matrix} n+2 \\ r \\ \end{matrix} ) $
D) $ ( \begin{matrix} n+2 \\ r \\ \end{matrix} ) $
Correct Answer: D
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Answer:
Solution:
BETA
