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Math Help - Logs

  1. #1
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    Logs

    Log(base a)2=x
    Log(base a)5=y

    find log(base 2)5?

    How would you do this?
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  2. #2
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    e^(i*pi)'s Avatar
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    Quote Originally Posted by p4pri View Post
    Log(base a)2=x
    Log(base a)5=y

    find log(base 2)5?

    How would you do this?
    Use the change of base rule:

    \log_b(a) = \frac{\log_c(a)}{\log_c(b)}

    You should find that a cancels

    As an example x = \log_a(2) = \frac{\log_2(2)}{\log_2(a)} = \frac{1}{\log_2(a)}
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  3. #3
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    Therefore, from what p4pri has said,

    log(base 2) 5 = (log(base a)5)/(log(base a)2) = y/x
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