Dear Student, C2n+1=n+1!2!n+1-2! =n+1!2n-1! =n+1nn-1!2n-1! =nn+12⇒C2n+1=nn+12 Hope this would have clear your doubt Do let us know in case of any further concerns

n+1C2=?

Dear Student,

{}^{n + 1}C_{2} = \frac{(n + 1)!}{2! (n + 1 - 2)!} = \frac{(n + 1)!}{2 (n - 1)!} = \frac{(n + 1) n (n - 1)!}{2 (n - 1)!} = \frac{n (n + 1)}{2} \Rightarrow {}^{n + 1}C_{2} = \frac{n (n + 1)}{2}

Hope this would have clear your doubt. Do let us know in case of any further concerns.

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n+1C2=? ​

n+1C2=?