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Homework Help: Does anyone know how to solve this log question ?

  1. Jan 21, 2009 #1
    show how
    Last edited: Jan 21, 2009
  2. jcsd
  3. Jan 21, 2009 #2


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    Multiply both sides by 2, 2*log((x-y)/3)=log(x)+log(y). Now what? Show us what you try.
  4. Jan 21, 2009 #3


    Staff: Mentor

    log((x - y)/3) = 1/2(log x + log y)
    ==> log((x - y)/3) = 1/2(log xy)
    ==> log((x - y)/3) = log (xy)1/2

    Now, if the logs of two numbers are equal, then the two numbers must be equal. (Equivalently you could exponentiate each side of the equation; that is, make each side the exponent on 10. 10log a = a as long as a > 0.
  5. Jan 21, 2009 #4
    Thank-you so much.
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