the sum of first 14 terms of an ap is 1505 and the term is minus 1 find the sum of first 16 terms of the AP

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the sum of first 14 terms of an ap is 1505 and the term is minus 1 find the sum of first 16 terms of the AP

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Margaret 1 week 2021-09-09T13:19:41+00:00 1 Answer 0 views 0

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    2021-09-09T13:21:19+00:00

    Sum of n terms =Sn= n/2 [2a+(n-1)d] where a =first term d =common different

    Therefore ,S14 =14/2 [ 2*10+(14-1)d]=1505

    Sole for d, we get, 215 =20 +13d hence ,d =15

    Now,an =a+(n-1) d

    Therefore,a25 =10+(25-1)15

    a25=10+24*15=370

    pls brainliest

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