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Homework Help: Complex expressions

  1. Oct 11, 2013 #1
    Hello I'm studying complex numbers for class and the question is stated as:
    Let z=1+2i
    a) 1/z^2
    b) 1/z^3

    I was thinking just to multiply by the conjugate (1-2i)^2 for (a) and similarly for (b).
    Would that be correct in solving it?
  2. jcsd
  3. Oct 11, 2013 #2


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    Staff: Mentor

    You can do that, right.
    Alternatively, calculate 1/z first, and then calculate powers of that.

    As this looks like homework, I moved your thread.
  4. Oct 11, 2013 #3
    Oh thank you!
    I apologize if I put it in the wrong thread!
  5. Oct 12, 2013 #4
    Firstly, let's establish what you are actually asking.

    For example, the way you wrote it, 1/z^2 = [itex]\frac{1}{z^2}[/itex], NOT [itex](\frac{1}{z})^2[/itex]

    EDIT: Please ignore. Complete brain-fart by me there! :redface:
    Last edited: Oct 12, 2013
  6. Oct 12, 2013 #5


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    Staff: Mentor

    Where is the difference?
  7. Oct 12, 2013 #6
    Thanks. I simply cannot believe what I wrote in my previous post.

    I blame lack of sleep...:zzz:
  8. Oct 12, 2013 #7


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    Surely there must be some way to completly delete a post so that those of us who post a really stupid idea can pretend it never happened!?
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