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Homework Help: Complex numbers

  1. Jun 28, 2008 #1
    Ok this is something i learned few years ago and im a bit rusty.

    So i have to find the absolute value of:

    [tex]\frac{1 - 2i}{3 + 4i}[/tex] + [tex]\frac{i - 4}{6i - 8}[/tex]

    So first i add the two fractions and i get:

    [tex]\frac{(1 - 2i)(6i - 8) + (i - 4)(3 + 4i)}{(3 + 4i)(6i - 8)}[/tex]

    Next i simplify and then i find the absolute value of the complex numbers above and below
    Is this correct, because i have forgoten.
  2. jcsd
  3. Jun 28, 2008 #2
    First combine the two expressions into one 'a +ib' form.
  4. Jun 28, 2008 #3
    Ok I solved it, sorry for the stupid question
  5. Jun 28, 2008 #4


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    Science Advisor

    Actually you don't need to "combine the two expressions into one 'a+ ib' form in order to find the absolute value and here it may be better not to.
    [tex]\left|\frac{a}{b}\right|= \frac{|a|}{|b|}[/tex]
    so you don't need to get rid of the "i" in the denominator.
  6. Jun 29, 2008 #5
    I was emphasising on the basics sir.
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