Find the sum `S_(n)` of cubes of first n terms o fan A.P.and show that the sum of first n terms of A.P.is a factor of `S_(n)`.

If the n^(th) term of an A.P.is (2n+1), find the sum of first n terms of the A.P.

In the sum of first n terms of an A.P.is cn^(2), then the sum of squares of these n terms is

The sum of first n terms of an A.P.is 5n-n^(2) . Find the nth term of this A.P.

If the sum of first n terms of a G.P. is s and the sum of its first 2n terms is 5S, then show that the sum of its first 3n terms is 21S .

If the sum of first n terms of a G.P. is S and the sum of its first 2n terms is 5S, then show that the sum of its first 3n terms is 21S.

If the sum of first 7 terms of an A.P. is 49 and that of 17 terms is 289, find the sum of first n terms.

The sum of first p- terms terms of an A.P.is q and the sum of first q terms is p,find the sum of first (p+q)

If the sum of first 7 terms of an A.P. is 49 and that of its 17 terms is 289, find the sum of first n terms of the A.P.

The sum of the first n terms of an A.P.is 4n^(2)+2n. Find the nth term of this A.P.