how many terms of the series 9+12+15....should be added to get the sum

1.	how many terms of the series 9+12+15....should be added to get the sum as 306
Answer» A/C to question,9 + 12 + 15 + ....... n terms = 306you can see that ,common difference of the series is always equal to 3 . e.g (12 - 9) = (15 - 12) = 3so, this series is in AP .now,Let total number of terms = n in such a way that sum of n terms = 306.we know,here, a = 9 , d = 3 and Sn = 306now,

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