The sum of the first three terms of an arithmetic progression is 9 and the sum of their squares is 35. The sum of the first n terms of the series can be

the sum of the first seven terms.

The sum of the first three terms of an increasing G.P. is 21 and the sum of their squares is 189. Then the sum of its first n terms is

Find the sum of the first 28 terms of the series.

If the sum of the first 4 terms of an arithmetic progression is p, the sum of the first 8 terms is q and the sum of the first 12 terms is r, express 3p+r in terms of q.

The sum of the first three terms of a strictly increasing G.P. is alphas and sum of their squares is s^2

The sum of the first three consecutive terms of an A.P. is 9 and the sum of their squares is 35. Find S_(n)

The sum of the first fifteen terms of an arithmetical progression is 105 and the sum of the next fifteen terms is 780. Find the first three terms of the arithmetical progression,.

If the sum of the first 100 terms of an arithmetic progression is -1 and the sum of the even terms is 1, then the 100^("th") term of the arithmetic progression is

If the sum of the first 23 terms of an arithmetic progression equals that of the first 37 terms , then the sum of the first 60 terms equals .

The sum of the first three terms of an Arithmeic Progression (A.P.) is 42 and the product of the first and third term is 52. Find the first term and the common difference.