What is the sum of first n terms of the AP a, 3a, 5a,….

What is the sum of first 10 terms of the A.P. 15, 10 ,5 ….?

If the sum of the first 2n terms of the AP 2, 5, 8 ....is equal to the sum of first n terms of the AP 57, 59, 61, ..., then what is the value of n?

Find the sum S_n of the cubes of the first n terms of an A.P. and show that the sum of first n terms of the A.P. is a factor of S_n .

If the sum of first 2n terms of the A.P. 2, 5, 8,…. Is equal to the sum of the first n terms of the A.P. 57, 59, 61,… then find n.

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

If the sum of the first 2n terms of the AP 2,5,8.....is equal to the sum of the first n terms of the AP 57,59,61, ....then n equals

What is the sum of first n terms of an A.P. whose first term is 'a' and common difference is 'd'?

If the sum of the first 2n terms of the A.P. 2,5,8, "……….." is equal to the sum of the first n terms of the A.P. 57,59,61, "…………" then n equals :

If the sum of the first 2n terms of the A.P. 2, 5, 8, ..., is equal to the sum of the first n terms of A.P. 57, 59, 61. .... then n equals