If `S_n`, be the sum of `n` terms of an `A.P`; the value of `S_n-2S_(n-1)+ S_(n-2)`, is

If S_n , denotes the sum of n terms of an AP, then the value of (S_(2n)-S_n) is equal to

If S_n, denotes the sum of n terms of an A.P. , then S_(n+3)-3S_(n+2)+3S_(n+1)-S_n=

If S_n denotes the sum of first n terms of an A.P. and (S_(3n)-S_(n-1))/(S_(2n)-S_(2n-1))=31 , then the value of n is a. 21 b. 15 c.16 d. 19

If S_n denotes the sum of first n terms of an A.P. and (S_(3n)-S_(n-1))/(S_(2n)-S_(2n-1))=31 , then the value of n is 21 b. 15 c.16 d. 19

If S_(n) denotes the sum of first n terms of an AP, then prove that S_(12)=3(S_(8)-S_(4)).

If S_n denotes the sum of n terms of A.P., then S_(n+3)-3S_(n+2)+3S_(n+1)-S_n= (a) S_2-n b. S_(n+1) c. 3S_n d. 0

If S_r denotes the sum of the first r terms of an A.P. Then, S_(3n)\ :(S_(2n)-S_n) is n (b) 3n (c) 3 (d) none of these

If S_n denotes the sum of first n terms of an A.P., prove that S_(12)=3(S_8-S_4) .

If S_n , the sum of first n terms of an A.P., is given by S_n=5n^2+3n , then find its n^(t h) term.

Let S_n denote the sum of first n terms of an AP and 3S_n=S_(2n) What is S_(3n):S_n equal to?