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-   -   Derivative for ln(x) (https://www.askmehelpdesk.com/showthread.php?t=538972)

  • Dec 30, 2010, 04:44 AM
    pop000
    1 Attachment(s)
    Derivative for ln(x)
    How do I find the Derivative for the Function.


    Thanks.
  • Dec 30, 2010, 12:39 PM
    ebaines

    The derivative of ln(x) is 1/x. I'm not sure what you're trying to get at with your formula:



    This formula is incorrect, so please clarify your question.
  • Dec 30, 2010, 01:59 PM
    pop000
    hi. I know that the derivative of ln(x) is 1/x. but the original question was to prove that the Function ln(x)=1/x-1 has exactly 2 Solutions

    I need to find the derivative.


    hope is more clear now :)
  • Dec 30, 2010, 03:16 PM
    galactus

    You can use the Intermediate Value Theorem and/or Rolles Theorem to prove it has two solutions.
  • Dec 30, 2010, 09:40 PM
    harum
    Would like to help you but have not a slightest idea what you want to do here.

    Equations ln(x) = 1/x-1 and ln(x) = -1/(x-1) are not the same, so it gets more and more confusing.

    The first equation has only one solution, the second -- none.
  • Dec 31, 2010, 04:54 AM
    galactus
    2 Attachment(s)

    You can rewrite it as:

    and then try to show this has exactly two solutions.

    The thing is, it does not have two solutions.

    But, if it were , then it would have the two solutions.

    Both graphs appear below.
  • Jan 1, 2011, 03:23 AM
    pop000
    OK I will try thanks to all of you for helping.

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