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Homework Help: Help with equation

  1. Dec 13, 2006 #1
    1. The problem statement, all variables and given/known data
    Decide the real value of x making Re(10 / x+4i) = 1

    2. Relevant equations
    I know that you can extend the equation with x-4i.

    3. The attempt at a solution
    But then the equation looks like this: (10x-40i) / (x^2 + 16) = 1
    I don't know how to get rid of the -40i to make it in to a real equation.

    Any help would be valuable!
  2. jcsd
  3. Dec 13, 2006 #2


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    [tex]\frac{10x-40i}{x^2+ 16}= \frac{10x}{x^2+16}-i\frac{40}{x^2+ 16}[/tex]
  4. Dec 13, 2006 #3
    It says the real part of (10x - 40i)/(x^2 + 16) = 10x/(x^2+16) - 40i/(x^+16). Take the real part of that and set it equal to 1, and solve for x.
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