If `D_k=1nn2k n^2+n+1n^2+n2k-1n^2n^2+n+1a n dsum_(k=1)^n D_k=56.` then `n` equals `4` b. `6` c. `8` d. none of these

If D_k=|[1,n,n],[2k,n^2+n+2,n^2+n],[2k-1,n^2,n^2+n+2]| and sum_(k=1)^n D_k=48 ,then n equals (a)4 (b) 6 (c) 8 (d) none of these

If Delta_k=|(1,n,n), (2k, n^2+n+1, n^2+n), (2k-1, n^2, n^2+n+1)| and sum_(k=1)^n Delta_k = 56, then n is equal to (i)4 (ii)6 (iii)8 (iv)none

if D_(k) = |{:( 1,,n,,n),(2k,,n^(2)+n+1 ,,n^(2)+n),(2k-1,,n^(2),,n^(2)+n+1):}|" and " Sigma_(k=1)^(n) D_(k)=56 then n equals

If Delta_(k) = |(k,1,5),(k^(2),2n +1,2n +1),(k^(3),3n^(2),3n +1)|, " then " sum_(k=1)^(n) Delta_(k) is equal to

if U_n = |[1 , k , k] , [2n , k^2+k+1 , k^2+k] , [2n-1 , k^2 , k^2+k+1]| and sum_(k=1->n)U_n=72 then value of k is:

If Delta_k=|(1,n,n),(2(k-1),n(n+1),n(n-1)),(4k(k^2-1),n(n+1)(n^2-4),n(n+2)(n^2-1))|, then f(n)=sum_(k=1)^n Delta_k+n is a polynomial of degree (i)0 (ii)1 (iii)6 (iv)7

The value of sum_(r=1)^(n+1)(sum_(k=1)^(k)C_(r-1))( where r,k,n in N) is equal to a.2^(n+1)-2b2^(n+1)-1c.2^(n+1)d. none of these