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If ""(n)C(r) denotes the number of combi...

If `""(n)C_(r)` denotes the number of combinations of n different things taken r at a time, then the vlaue of `""^(n)C_(r+1)+""^(n)C_(r-1) + 2. ""^(n) C_(r)` is-

A

`""^(n+1)C_(r + 1)`

B

`""^(n+2)C_(r )`

C

`""^(n+2)C_(r + 1)`

D

`""^(n+1)C_(r )`

Text Solution

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The correct Answer is:
C
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""^(n-2)C_(r)+2""^(n-2)C_(r-1)+""^(n-2)C_(r-2) equals :

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