Algebra 2

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Find a1 for the arithmetic series with Sn = 77, an=30, and n-7

  • Algebra 2 -

    Just as in your other post,

    Sn = n/2 (a1 + an)

    Only this time we want a1

    77 = 7/2 (a1 + 30)
    154 = 7a1 + 210
    -56 = 7a1
    a1 = -8

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