A) \[^{n+1}{{C}_{r}}\]
B) \[^{n+1}{{C}_{r+1}}\]
C) \[^{n+2}{{C}_{r}}\]
D) \[^{n+2}{{C}_{r+1}}\]
Correct Answer: C
Solution :
\[^{n}{{C}_{r}}+2{{}^{n}}{{C}_{r-1}}+{{\,}^{n}}{{C}_{r-2}}={{\,}^{n}}{{C}_{r}}+{{\,}^{n}}{{C}_{r-1}}+{{\,}^{n}}{{C}_{r-1}}+{{\,}^{n}}{{C}_{r-2}}\] \[={{\,}^{n+1}}{{C}_{r}}+{{\,}^{n+1}}{{C}_{r-1}}={{\,}^{n+2}}{{C}_{r}}\].You need to login to perform this action.
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