SOLUTION: Find the sum of the first 70 terms of the sequence -6, -3, 0, 3, 6

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Question 1034993: Find the sum of the first 70 terms of the sequence -6, -3, 0, 3, 6
Answer by fractalier(6550) About Me  (Show Source):
You can put this solution on YOUR website!
The formula for this is
S%5Bn%5D+=+%28n%2F2%29%28a%5B1%5D%2Ba%5Bn%5D%29+=+%28n%2F2%29%282a%5B1%5D+%2B+%28n-1%29d%29
S%5B70%5D+=+%2870%2F2%29%282%2A%28-6%29+%2B+%2870-1%29%2A3%29
S%5B70%5D+=+35%28-12+%2B+69%2A3%29+=+35%28195%29+=+6825