Results 1 to 3 of 3

Thread: derivative help

  1. #1
    Newbie
    Joined
    May 2010
    Posts
    10

    derivative help

    a little confused on this derivative, my professor posted the answers and he has this answer as $\displaystyle \frac{-19}{112}$ but i'm not seeing how he's getting that. any help is really appreciated.

    find the derivative and $\displaystyle f\prime(2)$

    $\displaystyle f(x) = \frac{x^3+2x+3}{x^4+3x+6}
    $


    if i use product rule i get


    $\displaystyle


    f\prime(x) = \frac{(3x^2+2)(x^4+3x+6) - (x^3+2x+3)(4x^3+3)}{(x^4+3x+6)^2}$

    i've done it two different ways and come up with $\displaystyle \frac{-35}{784} or \frac{-133}{784}$


    please help, final is tomorrow !
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Member
    Joined
    Feb 2010
    Posts
    148

    derivative

    Hello,

    Your derivative is correct and $\displaystyle f'(2)=\frac{-133}{784}$
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Newbie
    Joined
    May 2010
    Posts
    10
    that's what i figured, he posted a couple answers that seemed a bit off so i assume he made mistakes. he's just giving me anxiety about how i'm solving these problems hahaha. thanks again
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. contuous weak derivative $\Rightarrow$ classic derivative ?
    Posted in the Differential Geometry Forum
    Replies: 2
    Last Post: Apr 22nd 2011, 02:37 AM
  2. Replies: 0
    Last Post: Jan 24th 2011, 11:40 AM
  3. [SOLVED] Definition of Derivative/Alt. form of the derivative
    Posted in the Calculus Forum
    Replies: 2
    Last Post: Sep 23rd 2010, 06:33 AM
  4. Derivative of arctan in a partial derivative
    Posted in the Calculus Forum
    Replies: 3
    Last Post: Sep 12th 2010, 01:52 PM
  5. Replies: 2
    Last Post: Nov 6th 2009, 02:51 PM

Search Tags


/mathhelpforum @mathhelpforum