"If `S_n` denotes the   sum of the first `n` terms of an   A.P., prove that `S_(30)=3
Channel: Doubtnut
Date: 2020-06-28

"If `S_n`
 denotes the
 
  sum of the first `n`
 terms of an
 
  A.P., prove that `S_(30)=3(S_(20)-S_(10))`
 ."