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Homework Help: Lograthmic function

  1. Jan 27, 2006 #1
    Am trying to solve this natural log problem, where i have to find the value of x.

    ln (3+x)=7

    this is what i have done

    3+x= e7
    x= 1093.63

    This is the answer am getting, but its wrong. Can someone please let me know what am doing wrong, thanks.
  2. jcsd
  3. Jan 27, 2006 #2


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    Homework Helper

    Well the answer isn't 'wrong', but it's only an approximation, why not leave it as an exact answer? It seems that your method was ok...

    [tex]\ln \left( {3 + x} \right) = 7 \Leftrightarrow 3 + x = e^7 \Leftrightarrow x = e^7 - 3 \Leftrightarrow x \approx 1093.633158 \ldots [/tex]

    So instead of doing that last stap (see how I didn't the equality sign?) just leave it as [itex]x = e^7 - 3[/itex].
  4. Jan 28, 2006 #3
    Thanks for ur help.
  5. Jan 29, 2006 #4


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    Homework Helper

    You're welcome :smile:
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