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: Simple Question on Natural Logarithms

  1. Nov 16, 2006 #1
    Hey, I really would appreciate some help with this one as I'm stuck on my coursework. It'll probably be easy for most of you but I forgot how to do this operation with logarithms. See this equation:

    lny = lnx + BlnK + (1 - B)lnL.

    How can I change that to one that removes the natural logarithms by means of using x = e^lnx? Thanks in advance!
  2. jcsd
  3. Nov 16, 2006 #2
    Thank you very much!
  4. Nov 16, 2006 #3


    User Avatar
    Science Advisor

    This is really hilarious! You ask for someone to do your homework for you, showing absolutely no work of your own, then someone gives you a WRONG answer and you accept it without a thought!

    ea+b is NOT equal to ea+ eb!

    But A ln x= ln xA and ln x+ ln y= ln xy. Use those to write the left hand side as a single logarithm.
    Last edited by a moderator: Nov 16, 2006
  5. Nov 17, 2006 #4
    HallsofIvy, please react proportionately to the situation. It was just a simple question and no big deal; the equation was just one out of a couple of alternatives I could solve to proceed with my coursework. I felt it was an insignifcant question so I didn't really believe it necessary to show all my workings. Nevertheless, thank you for your input.
  6. Nov 17, 2006 #5


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Curious, that is pretty proportional. The situation is extremely ironic, and from now on if someone posts a question without showing work, I'm going to offer three possible solution routes, only one of which is correct. Absolutely brilliant.
  7. Nov 17, 2006 #6
    Talking about sound judgement and proportionality...
  8. Nov 17, 2006 #7


    User Avatar
    Science Advisor

    Should I have said nothing and let you think you had a correct answer?
    I don't dislike you that much!

    I pointed out that you were making a mistake and explained how to get the correct answer. And you criticize me?
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook