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Math Help - Needs help with LOG expressions! for algebra

  1. #1
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    LOG expression

    write as a single logarithm: Ln5+2Lnx+4Ln(x^2+8)

    Ln(_______)
    i cant figure it out! i have trouble remembering what to do first



    if anyone can help me with these it would be greatly appreciated!
    thanks,
    Last edited by bharriga; April 17th 2008 at 01:00 PM. Reason: 1 last problem updated**!
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  2. #2
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    Quote Originally Posted by bharriga View Post
    ln(a+b)+3 ln(a-b)-5 ln c

    write as a single logarithm: ln ( )
    cant figure it out! i have trouble remembering what to do first


    also here is another similar problem:

    Log(2)X+4 Log(2)y-3 Log(2)z

    rewrite as single logarithm using this: Log2( )

    if anyone can help me with these it would be greatly appreciated!
    thanks,
    Use the properties of the logarithm:

    \ln(a+b) +3 \ln(a-b) - 5\ln(c) = \ln(a+b) + \ln((a-b)^3) - \ln(c^5) = \ln\left(\frac{(a+b)(a-b)^3}{c^5}\right)

    \log_2(x) + 4\log_2(y) - 3\log_2(z) = \log_2\left(\frac{x \cdot y^4}{z^3}\right)
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  3. #3
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    Quote Originally Posted by bharriga View Post
    Ln(a+b)+3 Ln(a-b)-5 Ln c

    write as a single logarithm: Ln (_______________)
    cant figure it out! i have trouble remembering what to do first


    also here is another similar problem:

    Log(2)X+4 Log(2)y-3 Log(2)z

    rewrite as single logarithm using this: Log2(________)

    if anyone can help me with these it would be greatly appreciated!
    thanks,

    It doesn't matter what you do first as long as move the coefficients to exponents...

    \ln(a+b)+3 \ln(a-b)-5\ln(c)

    \ln(a+b)+\ln((a-b)^3)-\ln(c^5)

    \ln \left(\frac{(a+b)(a-b)^3}{c^5}\right)
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  4. #4
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    or do his method!
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  5. #5
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    Quote Originally Posted by bharriga View Post
    ...
    i cant figure it out! i have trouble remembering what to do first

    ...
    Only in case you want to learn a little bit more about logarithms I've attached a pdf-file for you.
    Attached Files Attached Files
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