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Logrithmic question

  1. Apr 4, 2003 #1
    I'm having a hard time solving this:
    e^(x+3) = pi^x


    I got these results, but I'm not sure if it is correct:
    ln^(x+3) = ln(pi^x)
    (x+3)ln = xln(pi)
    xln + 3ln = xln(pi)
    3ln = xln(pi)-xln
    3ln = x(ln(pi) - ln)

    x = 3ln/ln(pi)-ln

    NOTE: PI =3.14 (I don't know how to insert the symbol pi)
     
  2. jcsd
  3. Apr 4, 2003 #2
    That's the right way to go about, but remember, ln is a function... you have to write ln(something), ln by itself is not a number.

    ln(e)=1

    and you should be able to get it from there...
     
  4. Apr 4, 2003 #3

    chroot

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    Staff Emeritus
    Science Advisor
    Gold Member

    Yeah, you're kinda butchering things with your "ln raised to a power" and "ln by itself" stuff.

    Step 1. Take the natural logarithm of both sides of the equation:

    ln(e^(x+3)) = ln(pi^x)

    this becomes

    x+3 = x * ln(pi)

    Step 2. Isolate x on one side of the equation

    3 = x * ln(pi) - x
    3 = x (ln(pi) - 1)

    Step 3. Solve for x

    x = 3 / (ln(pi) - 1)

    - Warren
     
  5. Dec 26, 2006 #4
    I'm having difficulty in solving for x,in the equation e^x=4-x^2
    help please
    lne^x=ln(4-x^2)
    x=ln(4-x^2) and this is as far as iI got
     
    Last edited: Dec 26, 2006
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