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Homework Help: May i know (cos n pi ) with n to infinity is converges or diverges?

  1. Feb 16, 2006 #1
    may i know (cos n pi ) with n to infinity is converges or diverges??

    may i know (cos n pi ) with n to infinity is converges or diverges??
     
  2. jcsd
  3. Feb 16, 2006 #2

    quasar987

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    Use the fact that if a sequence converges, the limit is unique, and the fact that if a sequence converges towards x, all subsequences converge towards x also.

    Can you find 2 subsequences of {cos npi} that converges towards different numbers?
     
  4. Feb 16, 2006 #3
    is it -1 and +1 ??
     
  5. Feb 16, 2006 #4

    quasar987

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    Is there a doubt in your mind?
     
  6. Feb 16, 2006 #5
    yaya.pls explain to me
     
  7. Feb 16, 2006 #6

    quasar987

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    Is this in the context of an analysis class?

    Are you familiar with the two theorems I quoted in my first post?
     
  8. Feb 16, 2006 #7
    no,what is subsequence??
     
  9. Feb 16, 2006 #8

    arildno

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    First answer my question, teng:
    What is meant by a "limit"?
     
  10. Feb 16, 2006 #9

    quasar987

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    I put this conversation in your hands arildno, I have to leave. :smile:
     
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