Results 1 to 5 of 5

Math Help - Find this derivative

  1. #1
    Newbie
    Joined
    Mar 2010
    Posts
    24

    Find this derivative

    Hi guys.

    Find the derivative of this function:

    |(x)/(1-x^2)|

    Thanks.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    -1
    e^(i*pi)'s Avatar
    Joined
    Feb 2009
    From
    West Midlands, England
    Posts
    3,053
    Thanks
    1
    Let u = x^2 \implies du = 2x dx \imples dx = \dfrac{du}{2x}

    \dfrac{x du}{2x(1-u)} = \dfrac{1}{2} \cdot \dfrac{1}{1-u}

    You'll still need to use the chain rule on that -u of course
    Follow Math Help Forum on Facebook and Google+

  3. #3
    MHF Contributor FernandoRevilla's Avatar
    Joined
    Nov 2010
    From
    Madrid, Spain
    Posts
    2,162
    Thanks
    45
    The function is:


    f(x)=\begin{Bmatrix} \dfrac{x}{1-x^2} & \mbox{ if }& x\in (-\infty,-1)\cup [0,1)\\{}\\\dfrac{x}{x^2-1} & \mbox{if}& x\in (-1,0)\cup (1,+\infty)\end{matrix}


    Fernando Revilla
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Senior Member
    Joined
    Nov 2010
    From
    Staten Island, NY
    Posts
    451
    Thanks
    2
    You can also use the chain rule together with the fact that the derivative of |x| is \frac{x}{|x|}.
    Follow Math Help Forum on Facebook and Google+

  5. #5
    MHF Contributor

    Joined
    Apr 2005
    Posts
    15,325
    Thanks
    1296
    Notice that |x| does NOT have a derivative at x= 0. The given function also does not exist at x= 1 and x= -1 and so does not have a derivative at x=-1, x= 0, and x= 1.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. find log derivative, then HA's
    Posted in the Calculus Forum
    Replies: 1
    Last Post: December 10th 2011, 08:34 PM
  2. Find the derivative of...
    Posted in the Calculus Forum
    Replies: 7
    Last Post: June 10th 2011, 04:58 AM
  3. find derivative
    Posted in the Calculus Forum
    Replies: 1
    Last Post: October 22nd 2008, 08:13 PM
  4. Find the derivative.
    Posted in the Calculus Forum
    Replies: 1
    Last Post: September 10th 2008, 06:18 PM
  5. find the Derivative
    Posted in the Calculus Forum
    Replies: 1
    Last Post: February 26th 2008, 05:35 PM

Search Tags


/mathhelpforum @mathhelpforum