Question 456 of 519MediumMCQ
If nC4, nC5 and nC6 are in A.P., then n can be :
Solutions · 1
Official solution
2.nC5 = nC4 + nC6
2.\[{n \over {\left| 5 \right|n - 5}} = {n \over {\left| 4 \right|n - 4}} + {n \over {\left| 6 \right|n - 6}}\]
\[{2 \over 5}.{1 \over {n - 5}} = {1 \over {\left( {n - 4} \right)\left( {n - 5} \right)}} + {1 \over {30}}\]
n=14 satisfying equation. Answer the question to unlock