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Math Help - log questions

  1. #1
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    log questions

    I have a few more log questions that I am stuck on. Any help is appreciated. Thanks

    1. Solve the the unknown value: log(ln(x))=0

    2. If g(x)=ln(x), find g(e^6.45)

    3. solve: 4^x+2=8
    (it is 4 to the x+2 power)

    thanks again
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  2. #2
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    Quote Originally Posted by mamajen View Post

    3. solve: 4^x+2=8
    (it is 4 to the x+2 power)
    4^{x+2}=8

    (2^2)^{x+2}=2^3

    2^{2(x+2)}=2^3

    2(x+2)=3

    Can you finish it?
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  3. #3
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    the question is in exponential form and needs to be solved for log form. I can solve for x but that doesn't give me the log form that it is wanting. here is how far i have gotten.....
    log base 4 (8) = x+2
    I am lost after that.
    I am not sure if that is how I need to solve it either.
    I have written in my notes that if it is in exponential form that you need to take the log base 10 of both sides. So I am not sure if I should solve it the way I have above or if I should go this way....
    log4x+2=log8
    Last edited by mamajen; May 2nd 2010 at 08:58 PM. Reason: add more info
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  4. #4
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    Consider a^b = c \implies b= \log_ac

    Therefore

    4^{x+2}=8


    x+2=\log_48

    x=\log_4(8) -2

    How is this?
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  5. #5
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    ok after much thinking i figured this out.
    you take the ln of both sides which will give you......
    (x+2) * ln(4)=ln(8) which then turns into.....

    x+2= ln8/ln4 then subtract the 2 on both sides gives you

    x= ln8/ln4 - 2

    x= -.5
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