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claireshowers

  • 4 years ago

What is the sum of a 17-term arithmetic sequence where the first term is 9 and the last term is -87?

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  1. sheg
    • 4 years ago
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    use the general formula of summation of an arithmetic series

  2. eSpeX
    • 4 years ago
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    S_n = 1/2 n(a_1 + a_n)

  3. eSpeX
    • 4 years ago
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    S_n = a_1 + d(a_n-1) is the other form I believe.

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