If the `10 t h` term of an A.P. is 21 and the sum of its first ten terms is 120, find its `n t h` term.

If the 10 th term of an A.P.is 21 and the sum of its first ten terms is 120, find its nth term.

The twelfth term of an A.P. is (-13) and the sum of its first four terms is 24, find the sum of first 10 terms of the A.P.

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

In an A.P., the sum of first n terms is (3n^2)/2+(13)/2n . Find its 25 t h term.

If the sum of first 20 terms of an A.P. is same as the sum of its first 28 terms, find the sum of its 48 terms.

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

If the n^(t h) term of an A.P., is (2n+1), then the sum of its first three terms is (a) 6n+3 (b) 15 (c) 12 (d) 21

If the n^(t h) term of an A.P., is (2n+1), then the sum of its first three terms is (a) 6n+3 (b) 15 (c) 12 (d) 21

If the n^(t h) term of an A.P., is (2n+1), then the sum of its first three terms is (a) 6n+3 (b) 15 (c) 12 (d) 21

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.