Find the sum of 19 terms of an A.P. Whose nth term is 2n+1.

Find the sum of first n terms of an A.P. whose nth term is 3n+1.

Find the sum of 40 terms of an A.P. whose third term is 1 and 6th term is - 11.

Find the sum of 32 terms of an A.P. whose third term is 1 and the 6th term is -11.

Find the sum to n terms of the A.P. whose kth term is 5k + 1.

Find the sum to n terms of the A.P., whose k^(th) term is 5k+ 1 .

If S_n denotes the sum of n terms of an A.P. whose first term is a, and the common difference is d Find: = Sn - 2Sn + S(n +2) .

Find the sum of n terms of the series whose nth term is : 2^(n+1)+4(n+1)(n-2) .

Find the sum of n terms of the series whose nth term is : 2^(n-1)-1 .

The sum of n terms of an A.P. whose first term is 5 and common difference is 36 is equal to the sum of 2n terms of another A.P. whose first term is 36 and common difference is 5. Find n.

Find the sum of n terms of the series whose nth terms is (i) n(n-1)(n+1) .