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Log prbolems

  1. Jun 6, 2009 #1
    1. The problem statement, all variables and given/known data

    1/2*log(5)(x^2-1)=1/4+1/2log(5)(x-1)

    I have put the base to the log in the first set of brackets following log.

    The question is simply solve for x the equation

    3. The attempt at a solution

    I firstly moved the logs onto the smae side and then multiplied both sides by1/2 (not shown) thus giving

    log(5)(x^2-1)-log(5)(x-1)=1/2

    log(5)((x^2-1)/(x-1))=1/2

    Am i right in the saying the follwoing is the next step?

    (x2-1)/(x-1)=5^(1/2)

    If I am then can someone please help me understand how I am supposed to simplify the equaiton down to give a single x.

    Thanks in advance.
     
  2. jcsd
  3. Jun 6, 2009 #2
    Re: Log problems

    Assuming that log(5) is log5, that is right. How can you rewrite
    [tex]\frac{x^2-1} {x-1}[/tex]

    specifically the numerator?
     
  4. Jun 6, 2009 #3
    That was exactly what I meant with regards to the base of the log.

    I'm sorry I don't follow. I think I am looking to hard into this problem as I can see no way of simplifying (x2-1)/(x-1)
     
  5. Jun 6, 2009 #4
    Do you know how to factor x2 - 1?
     
  6. Jun 6, 2009 #5

    HallsofIvy

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    Staff Emeritus
    Science Advisor

    You have
    [tex]\frac{x^2- 1}{x- 1}= \sqrt{5}[/tex]

    What Bohrok is suggesting is that you factor the numerator. There is a simple cancelation.
     
  7. Jun 7, 2009 #6
    All sorted now.

    Thanks very much for the sanity checks with this.
     
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