Q.

If 1n+1Cnn+1nCn-1n+....+12C1n+C0n=102310, then n is equal to                  [2023]

1 8  
2 9  
3 6  
4 7  

Ans.

(2)

1n+1Cnn+1nCn-1n++C0n

=r=0nCrnr+1=1n+1r=0nCr+1n+1=1n+1(2n+1-1)=102310=210-110

So, n+1=10n=9