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Thread: determine the range of ln equations

  1. #1
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    Unhappy determine the range of ln equations

    I need to determine the ranges of values of x and y for which the expressions on each side are defined please can I have help to start this off having a very bad day

    3ln(y+4)=2ln(x+2)-2ln(x+9)+3ln(x2-1)
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  2. #2
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    e^(i*pi)'s Avatar
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    It's defined when the argument is greater than 0.

    $\displaystyle y +4 > 0$

    $\displaystyle x+2 > 0$
    $\displaystyle x+9 > 0 $
    $\displaystyle x^2-1 > 0$

    Incidentally does anyone know how to get those in a table, like in matrices?
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  3. #3
    MHF Contributor FernandoRevilla's Avatar
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    Use the following:

    $\displaystyle \exists\;{\log u} \Leftrightarrow u>0$


    Fernando Revilla


    Edited: Sorry, I didn't see e^(i*pi)'s post
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  4. #4
    MHF Contributor FernandoRevilla's Avatar
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    Quote Originally Posted by e^(i*pi) View Post
    Incidentally does anyone know how to get those in a table, like in matrices?
    Do you mean something lihe this?


    $\displaystyle \begin{tabular}{| c | c | c | c | }
    \hline
    {$y+4>0$} & {$x+2>0$} & {$x+9>0$} & {$x^2-1>0$} \\
    \hline
    {$y>-4 $}&{$\ldots$}&{$\ldots $}&{$\ldots $} \\
    \hline

    \end{tabular}
    $


    Fernando Revilla
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  5. #5
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    e^(i*pi)'s Avatar
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    Quote Originally Posted by FernandoRevilla View Post
    Do you mean something lihe this?


    $\displaystyle \begin{tabular}{| c | c | c | c | }
    \hline
    {$y+4>0$} & {$x+2>0$} & {$x+9>0$} & {$x^2-1>0$} \\
    \hline
    {$y>-4 $}&{$\ldots$}&{$\ldots $}&{$\ldots $} \\
    \hline

    \end{tabular}
    $


    Fernando Revilla
    I mean where they're under each other in a line. It doesn't really matter that much, I think I made my point but thanks anyway
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