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Homework Help: Find the rth term of this sequence

  1. Jul 21, 2006 #1
    Given a sequence:
    3,33,333,3333,..........
    Find the rth term of this sequence.

    This sequence does not belong to Geometry Progression or Arithmetic Progression. From what I know, rth term is equals to (r-1)*10 +3.

    But how do I solve this problem?
     
  2. jcsd
  3. Jul 21, 2006 #2
    Hint:
    [tex]\sum\limits_{k = 0}^n {r^k } = \frac{{1 - r^{n + 1} }}{{1 - r}}[/tex]

    The rth term of your sequence is just (10r-1)/3 :smile:
     
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