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Math Help - can some one explain these logs please

  1. #1
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    Exclamation can some one explain these logs please

    i do not understand the reasoning behind the following problem, can someone please help??

    log(sub5) X = log X/log 5

    i didnt know how to make the 5 little and low btw, thats why it says sub,
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  2. #2
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    what you posted looks like the change of base formula where given a log_5(X) you take the natural log, that being the inverse function of the exponential, lnx/ln5. I think that what your trying to do...
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  3. #3
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    Quote Originally Posted by freepancakes View Post
    i do not understand the reasoning behind the following problem, can someone please help??

    log(sub5) X = log X/log 5

    i didnt know how to make the 5 little and low btw, thats why it says sub,
    \log_5 X = y \Rightarrow X = 5^y \Rightarrow \log X = \log 5^y = y \log 5 \Rightarrow y = \frac{\log X}{\log 5}.

    Therefore \log_5 X = \frac{\log X}{\log 5}.
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