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How was this log solved?

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  1. May 6, 2016 #1
    1. The problem statement, all variables and given/known data

    solve the log x²-4x-5 on the base x-2.


    2. Relevant equations

    I read a comment from someone that also saw the question that says:
    3. The attempt at a solution

    If it was x²-4x+4, that would be igual (x-2)² and the answer would be 2, but I have no idea the guy got these broken numbers. Making what equal to zero?
    the x²-4x-5? Doesn't make sense.
     
  2. jcsd
  3. May 6, 2016 #2

    SammyS

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    First of all: There is no equation to be solved in your thread.

    Second: x2 − 4x − 5 can be factored quite nicely.

    Third: What do you mean by " base x-2 " ?

    Added in Edit:

    Fourth: x = 5.1623 , −1.1623 are approximate solutions to x2 − 4x − 6 = 0 .
     
    Last edited: May 6, 2016
  4. May 6, 2016 #3

    haruspex

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    Where does the question come from?
     
  5. May 8, 2016 #4
    It's the base of the log, [itex](x-2) ^ {y} = x² -4x -5[/itex]. The statement is to solve it.

    From a video where the presenter receives random questions about several subjects. Someone asked it, a comment about it mentioned the roots and I got curious about whether this has a solution or not.
     
  6. May 8, 2016 #5

    haruspex

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    Ok, so we should not be too surprised that the question makes no sense.
     
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