If sum of first n terms of an AP is `2n^(2)+5n.` Then find `S_(20)`

If S_(n) the sum of first n terms of an AP is given by 2n^(2)+n, then find its nth term.

If the sum of first n terms of an A.P. is 3n^2 + 2n , find its r^(th) term.

If S_n the sum of first n terms of an AP is given by 2n^2+n , then find its nth term.

The sum of first n terms of an A.P. is 5n^(2) + 3n . If the nth term is 168, find the value of n. Also find the 20th term of the A.P.

The sum of first n terms of an AP is (5n - n^(2)). The nth term of the AP is

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

Let S_(n) be the sum of first n terms of an A.P. If S_(2n) = 5s_(n) , then find the value of S_(3n) : S_(2n) .

If S_(n) the sum of first n terms of an A.P. is given by Sn = 3n^(2) - 4n , find the nth term.

The sum of first n terms of an AP is (3n^2+6n) Find the n^(th) term and 15^(th) terms of the AP

Given sum of the first n terms of an A.P is 2n+ 3n^(2) . Another A.P is formed with the same first term and is double the common difference, the sum of n terms of the new A.P. is