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Homework Help: Copmlex Number

  1. Apr 9, 2009 #1
    i've confused myself

    [itex]\frac{1}{i}=-i[/itex] by multiplying by i/i

    but then [itex](\frac{1}{i})^2=-1 \Rightarrow \frac{1}{i}= i,-i[/itex]
    and clearly the positive root here doesn't make any sense???
     
  2. jcsd
  3. Apr 9, 2009 #2
    You are correct but you forgot to take the negative root of the left hand side.
     
  4. Apr 9, 2009 #3

    Pengwuino

    User Avatar
    Gold Member

    Well you've somewhat answered your own question. You simply did pick the incorrect root as there are always 2 roots to a square root

    [tex]\[
    \begin{array}{l}
    3 = 3 \\
    3^2 = 3^2 \\
    9 = 9 \\
    \sqrt 9 = \sqrt 9 \\
    3 = - 3? \\
    \end{array}
    \]
    [/tex]

    for example.
     
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