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Math Help - Log help

  1. #1
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    Log help

    Hi ,

    Could use some advise on ideas on how to solve this math question;
    log14=a log15=b and log 16=c

    Now I have to write an expression for each of the following in terms of a, b and c

    log 2 ( solved ) = c/4
    log 3 = (help me out here)
    log 4= c/2
    log 5= (help again)
    log6= help one more time
    log 7= a-(c/4)
    log 8= c-(c/4)
    log 9= again help......

    If anyone can point me in a direction to help solve the missing expressions I sure could use it. Have been working hours on this....

    Marty
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  2. #2
    Forum Admin topsquark's Avatar
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    Quote Originally Posted by Mjay View Post
    Hi ,

    Could use some advise on ideas on how to solve this math question;
    log14=a log15=b and log 16=c

    Now I have to write an expression for each of the following in terms of a, b and c

    log 2 ( solved ) = c/4
    log 3 = (help me out here)
    log 4= c/2
    log 5= (help again)
    log6= help one more time
    log 7= a-(c/4)
    log 8= c-(c/4)
    log 9= again help......

    If anyone can point me in a direction to help solve the missing expressions I sure could use it. Have been working hours on this....

    Marty
    For logs 3 and 5 note that we have b = log(15) = log(3 * 5).

    For log 9 note that 9 = 3^2, so log 9 = log (3^2) = 2 * log(3)...

    -Dan
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  3. #3
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    Ok,

    so then I calculate that 2(b-log5)=log3 but how do I find an expression using only a, b, c for log 5?
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  4. #4
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    If we can assume that \log(x) is really \log_{10}(x) then you know that \log(2)+\log(5)=1.
    Otherwise, there is something missing.
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  5. #5
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    Thank you ! Thank you! Thank You! Completely forgot that log 10=1. Knew we were missing something.....
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