In an A.P. if a=2, `t_(n)=34 ,S_(n) =90`, then n=

S_n in A.P.=

In an A.P., if a = 1 , a_(n) = 20 and S_(n) = 399 , then n = ……..

In an AP : Given a=2, d=8 , S_(n)=90 , find n and a_n .

S_(n) denote the sum of the first n terms of an A.P. If S_(2n)=3S_(n) , then S_(3n):S_(n) is equal to

In an A.P: given a = 2 , d = 8 , S_(n)= 90 , find n and a_(n) .

If S_(n) denotes the sum of first n terms of an A.P. and S_(2n)= 3S_(n) , then (S_(3n))/(S_(n))=

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) .

Let S_(n) denote the sum of the first n terms of an A.P. If S_(2n) = 3S_(n) , then S_(3n) : S_(n) is equal to :