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In Complex Numbers

  1. Apr 17, 2008 #1
    hi,
    please help me
     

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  2. jcsd
  3. Apr 17, 2008 #2
    Please show work attempting to the problem.
     
  4. Apr 17, 2008 #3
    I want the understanding of way that led us to this result
     
  5. Apr 17, 2008 #4
    @m s a: yeah.. we get that.. and what we need is that you show that you've solved something in this problem.. or atleast made an effort in this direction.
     
  6. Apr 17, 2008 #5
    If I was knowing the way to what asked
     
  7. Apr 17, 2008 #6

    Hootenanny

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    m_s_a,

    According to the Physics Forums Global Guidelines you are required to show an attempt or detail your thoughts on a homework question before we can provide assistance.

    You just have some idea how to prove the identity or else you wouldn't have been asked to prove it.
     
  8. Apr 17, 2008 #7

    Dick

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    m_s_a, if you are really blocked, tell us the relation between log and exp, and then reflect on it.
     
  9. Apr 17, 2008 #8

    Dick

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    Things would go much faster if you could convey simple information in some other way besides .bmp attachments. Those have to be approved before anyone can see them.
     
  10. Apr 17, 2008 #9
    like this:
     

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    • log.bmp
      log.bmp
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  11. Apr 18, 2008 #10

    Hootenanny

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    m_s_a, can you write a general complex number, z, in exponential form?
     
  12. Apr 18, 2008 #11

    HallsofIvy

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    So you are saying
    If y= ln(z) then z= ey

    Now, if y= a+ bi, what is ey?
    (and remember that ep+q= epeq)
     
  13. Apr 23, 2008 #12
    I came to this result then do it is right or no ?
     

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  14. Apr 23, 2008 #13

    HallsofIvy

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    Is there some reason why you insist upon posting attachments after you have been told its a bad idea?
    It's not all that difficult to type:
    (this would look much nicer in LaTex but I have typed it in ASCII)
    z= |z|e^(i theta)
    ln z= ln |z| e^(i theta) (Well, ln z= ln(z e^(i theta)) is correct)
    ln z= ln |z|+ ln(e^i theta)
    ln z= ln |z|+ i ln(theta)

    i.e. log(z)= ln z

    Assuming that your textbook has specified a convention that natural logarithm applied to complex numbers will be designated by "log", which is implied by the question itself, then it is not correct to write "ln z". Other than that, what you wrote is correct.
     
    Last edited: Apr 23, 2008
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