SOLUTION: Find the sum of the following arithmetic series 3+9+15+21+...+57 The sum of this series is

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Question 465630: Find the sum of the following arithmetic series
3+9+15+21+...+57
The sum of this series is

Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!
 
Hi
3+9+15+21+...+57
arithmetic series, d= 6
a%5Bn%5D=a%5B1%5D%2B%28n-1%29%2Ad
57 = 3 + (n-1)6
60 = 6n
n = 10, 57 is the 10th term
S%5Bn%5D=%28n%2F2%29%282%2Aa%5B1%5D%2B+%28n-1%29d%29
S%5B10%5D=%2810%2F2%29%282%2A3%2B+%289%296%29
S%5B10%5D=5%2A60+=+300+%29