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Find the sum of the first 33 terms of the arithmetic sequence whose first term is 3 and whose 33rd term is -253

  • math -

    As you (should) know,

    Sn = n/2 (a1 + an)
    S33 = 33/2 (a1 + a33)
    = 33/2 (3 - 253)
    = 33/2 (-250)
    = -33*125 = -4125

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