"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`
Channel: Doubtnut
Date: 2020-06-28

"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"