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Exponential laws logrithm function.

  1. Sep 1, 2010 #1
    find x for y=5

    y = -(((e^x)/(e^-x))/2) + ((e^x)/(e^(-3x))

    all i did was a^m / a^n = a^m-n

    i get here y = -1/2(e^(2x)) + (e^(4x))
    after this i get iffy and want to make sure i can do what i did.

    5 = -1/2(e^(2x)) + (e^(4x))
    ln|5|= -1/2(ln(e^2x)) + ln(e^4x)
    ln|5|= -1/2(2x) + 4x
    ln|5|= -x + 4x
    ln|5|= 3x

    x = ln|5|/3

    is this right?
     
  2. jcsd
  3. Sep 1, 2010 #2

    Mentallic

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    Homework Helper

    [tex]ln(a+b)\neq ln(a)+ln(b)[/tex]

    Substitute [tex]u=e^{2x}[/tex]
     
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