Results 1 to 2 of 2

Math Help - seemingly simple derivative

  1. #1
    Newbie
    Joined
    Oct 2009
    Posts
    14

    seemingly simple derivative

    hello all. my friend has asked me for help on a derivation but i've come up blank.

    the derivation in question is:

    \frac{d}{dx}lnx^{lnx}

    i thought lnx

    he thought 2\frac{lnx}{x}

    what do YOU think?
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Super Member redsoxfan325's Avatar
    Joined
    Feb 2009
    From
    Swampscott, MA
    Posts
    943
    Quote Originally Posted by makieru View Post
    hello all. my friend has asked me for help on a derivation but i've come up blank.

    the derivation in question is:

    \frac{d}{dx}lnx^{lnx}

    i thought lnx

    he thought 2\frac{lnx}{x}

    what do YOU think?
    It's \frac{2\ln x}{x}. Here's why:

    \ln\left(x^{\ln x}\right)=(\ln x)(\ln x)=(\ln x)^2

    Use the chain rule:

    2\ln x\cdot\frac{1}{x}=\frac{2\ln x}{x}
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. A seemingly simple proof
    Posted in the Differential Geometry Forum
    Replies: 3
    Last Post: July 8th 2010, 09:09 PM
  2. Help with a (seemingly?) simple proof.
    Posted in the Advanced Algebra Forum
    Replies: 6
    Last Post: May 27th 2009, 09:38 PM
  3. Another seemingly simple integral
    Posted in the Calculus Forum
    Replies: 5
    Last Post: February 25th 2009, 01:44 PM
  4. Intigrating this seemingly simple expression
    Posted in the Calculus Forum
    Replies: 2
    Last Post: April 3rd 2008, 05:53 PM
  5. Help with a seemingly simple math problem!
    Posted in the Pre-Calculus Forum
    Replies: 4
    Last Post: August 14th 2007, 11:01 PM

Search Tags


/mathhelpforum @mathhelpforum