Results 1 to 2 of 2
Like Tree1Thanks
  • 1 Post By HallsofIvy

Thread: typo checking ....

  1. #1
    Member
    Joined
    May 2009
    Posts
    243
    Thanks
    3

    typo checking ....

    I am asked to differentiate $y = 2x^x$

    taking logs to base e

    $\ln y = x \ln 2x $

    implicit differentiation

    $\dfrac{1}{y} \dfrac{dy}{dx} = x \dfrac{2}{2x} + 1. \ln 2x $

    $\dfrac{1}{y} \dfrac{dy}{dx} = 1 + \ln 2x $

    $\dfrac{dy}{dx} = 2x^x (1 + \ln 2x) $

    I think this is the right answer. The answer given is $2x^x ( 1 + \ln x) $ am I doing something wrong is it a mistake in the answer?
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor

    Joined
    Apr 2005
    Posts
    20,054
    Thanks
    3184

    Re: typo checking ....

    Your first step is incorrect. If $\displaystyle y= 2x^x$ then $\displaystyle log(y)= log 2+ x log(x)$. The "2" is NOT raised to the x power.
    Thanks from s_ingram
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Typo on Video?
    Posted in the Calculus Forum
    Replies: 1
    Last Post: Apr 23rd 2015, 02:54 AM
  2. Recursion or typo?
    Posted in the Math Forum
    Replies: 3
    Last Post: Jun 12th 2012, 06:58 PM
  3. Wondering if this is a typo?
    Posted in the Number Theory Forum
    Replies: 1
    Last Post: Apr 30th 2009, 02:01 PM
  4. HW typo--
    Posted in the Calculus Forum
    Replies: 3
    Last Post: Mar 22nd 2006, 10:35 AM

/mathhelpforum @mathhelpforum