Math, asked by draculawithinu, 1 year ago

find the sum of all given terms of the AP 5,8,11,14...47

Answers

Answered by lipi
7
here there are 15 terms
so  here a=5 d=3 n=15
so Sn=n/2[2a+(n-1)d]
          =15/2[10+(15-1)3}
           =15/2 *[52]
            =780/2
            =390
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