SOLUTION: Find the sum of the first 60 terms of the arithmetic sequence whose first term is -15 and whose common difference is 5

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Question 672675: Find the sum of the first 60 terms of the arithmetic sequence whose first term is -15 and whose common difference is 5
Answer by Edwin McCravy(20056) About Me  (Show Source):
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Sn = n%2F2[2·a1 + (n-1)·d]

where n=60, a1=-15, and d=5

S60 = 60%2F2[2·(-15) + (60-1)·5]

S60 = 30[-30 + 59·5]

S60 = 30[-30 + 295]

S60 = 30[265]

S60 = 7950

Edwin