SOLUTION: What is the answer to find the sum of the first 70 terms of the arithmetic sequence 45, 39, 33, 27?

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Question 370519: What is the answer to find the sum of the first 70 terms of the arithmetic sequence 45, 39, 33, 27?
Answer by stanbon(75887) About Me  (Show Source):
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What is the answer to find the sum of the first 70 terms of the arithmetic sequence 45, 39, 33, 27
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1st term: a = 45
Common difference: d = -6
n = 70
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last = a(70) = 45+(69)(-6) = -369
S(n) = (n/2)(a + last)
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S(70) = (70/2)(45-369)
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S(70) = 35(-324) = -11340
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Cheers,
Stan H.