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Math Help - Natural Log ?'s

  1. #1
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    Natural Log ?'s

    1. if lnx+ln(x-6) = ln3x then x= ????

    2. if ln(4x+2)=5 then x= ???
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  2. #2
    Moo
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    Hi

    for the first one use the following properties :

    ln(a)+ln(b)=ln(ab)
    if ln(a)=ln(b) then a=b

    So here x(x-6)=3x


    For the second one, if ln(a)=b, then a=e^b (if it's natural logarithm)
    -> 4x+2=e^5
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    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by phil S View Post
    1. if lnx+ln(x-6) = ln3x then x= ????
    \ln x + \ln (x - 6) = \ln 3

    \Rightarrow \ln x(x - 6) = \ln 3x

    now what? can you continue?

    2. if ln(4x+2)=5 then x= ???
    \ln (4x + 2) = 5

    \Rightarrow e^5 = 4x + 2

    i think you can take it from here
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