Results 1 to 3 of 3

Thread: derivative.

  1. #1
    Member
    Joined
    Jul 2009
    Posts
    149

    derivative.

    I have an equation

    $\displaystyle y =\frac{2x-5}{(3x+2)^2} $

    so i have to differentiate it.

    I think i am supposed to use the quotient rule

    $\displaystyle (\frac {f}{g})' = \frac{gf'-fg'}{g^2}$


    but i am confused about g'

    In trying to differentiate it i come up with this
    Expanded g.

    $\displaystyle (3x+2)(3x+2)$


    Then multiply out


    $\displaystyle = 9x^2 +6x+6x+4$

    $\displaystyle =9x^2+12x$

    $\displaystyle =18x +12x$

    so g' =20 x

    Is this correct? I have a feeling ive done somthing wrong. Im just trying to work out g' so i can plug it into the equation.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor
    skeeter's Avatar
    Joined
    Jun 2008
    From
    North Texas
    Posts
    16,216
    Thanks
    3701
    $\displaystyle g(x) = 9x^2 + 12x + 4$

    $\displaystyle g'(x) = 18x+12$
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Member
    Joined
    Jul 2009
    Posts
    149
    Quote Originally Posted by skeeter View Post
    $\displaystyle g(x) = 9x^2 + 12x + 4$

    $\displaystyle g'(x) = 18x+12$
    thanks.
    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 Increasing ==> Derivative Continuous
    Posted in the Differential Geometry Forum
    Replies: 2
    Last Post: Feb 23rd 2010, 10:58 AM
  5. Replies: 2
    Last Post: Nov 6th 2009, 02:51 PM

Search Tags


/mathhelpforum @mathhelpforum