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Homework Help: Testing convergence of sequence

  1. Oct 23, 2008 #1

    jlu

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    how can i can the convergence of sum[sin (0.4)n / n pi]2 and that sum[sin (0.4)n / n pi] diverges, n is between -infinity and + infinity
     
  2. jcsd
  3. Oct 23, 2008 #2

    mathman

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    The first series converges because it is dominated by 1/n^2 series, which is convergent. The second is harder - the 1/|n| series diverges, but this is only a clue.
     
  4. Oct 24, 2008 #3

    jlu

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    i used p-series test for the first one and root test for the second one. i stand to be corrected if i used the wrong rules
     
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