Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Solving logaritm equation

  1. Jan 25, 2012 #1
    I've run into a dead end trying to solve this equation and I was hoping that someone here might be able to point me in the right direction!

    1. The problem statement, all variables and given/known data
    xlgx = x4/1000


    2. Relevant equations
    -


    3. The attempt at a solution
    xlgx = x4/1000
    lg(xlgx) = lg(x4/1000)
    (lgx)2 = lg(x4) - lg(1000)
    (lgx)2 = 4lgx - 3

    Now after this point I'm not sure what to do. I tried:
    3 = 4lgx - (lgx)2
    3 = lgx * (4 - lgx)

    But that doesn't seem to lead me anywhere. Any help would be much appreciated!
     
    Last edited: Jan 25, 2012
  2. jcsd
  3. Jan 25, 2012 #2
    you have a quadratic equation in [itex]\log(x) [/itex]

    let [itex]t=\log(x)[/itex] and solve quadratic equation in t
     
  4. Jan 25, 2012 #3
    Of course, obviously!

    Thanks a lot for your help, much appreciated.
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook