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Homework Help: Algebra Help

  1. Aug 24, 2013 #1
    1. The problem statement, all variables and given/known data

    I can't follow the math of the very last line.
    It's really annoying me because I know its not supposed to be hard, I have tried multiplying top and bottom by k1+k2 and all kinds of rearranging but I'm not sure how they get from w1 - w2 / k1 - k2 = c (k1-k2) / (k1-k2)

  2. jcsd
  3. Aug 24, 2013 #2
    Given ω1/k1=c
    and ω2/k2=c right?
    On cross multiplying we'll get ω1=ck1 , ω2=ck2..
    Put these values in (ω12)/(k1-k2) And take c outside the bracket so as to arrive at c(k1-k2)/(k1-k2) which on simplification gives c ...
  4. Aug 24, 2013 #3

    Ray Vickson

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    Science Advisor
    Homework Helper

    They do not write
    [tex] \omega_1 - \frac{\omega_2}{k_1} - k_2[/tex]
    as you claim. They write
    [tex] \frac{\omega_1 - \omega_2}{k_1 - k_2}[/tex]
    which you can render in ASCII as (w1 - w2)/(k1-k2).
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