Results 1 to 2 of 2

Math Help - finding min max point.

  1. #1
    Newbie
    Joined
    Dec 2007
    Posts
    9

    Question finding min max point.

    hi!
    this is the function I'm looking at:

    f(x)= {(x^3-3x) /(1-x^2)}

    i got to f'(x)= (-x^4-3)/(1-x^2)
    and so I'm having a hard time finding the max and min
    (f'(x)=0)

    What am I'm doing wrong?

    thanks!
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Super Member
    earboth's Avatar
    Joined
    Jan 2006
    From
    Germany
    Posts
    5,830
    Thanks
    123
    Quote Originally Posted by Lilly100 View Post
    hi!
    this is the function I'm looking at:

    f(x)= {(x^3-3x) /(1-x^2)}

    i got to f'(x)= (-x^4-3)/(1-x^2)
    and so I'm having a hard time finding the max and min
    (f'(x)=0)

    What am I'm doing wrong?

    thanks!
    Hi,

    there is a small typo in your derivative:

    f'(x)=\frac{-x^4-3}{(1-x^2)^2}

    A quotient equals zero is the denominator is not zero and the nurmerator equals zero. Therefore you only have to solve for x:

    -x^4-3=0~\iff~x^4=-3 . This equation doesn't have any real root and that means your function hasn't any extreme values.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Replies: 4
    Last Post: September 8th 2010, 09:13 AM
  2. Finding closest point on line to a point
    Posted in the Geometry Forum
    Replies: 2
    Last Post: February 3rd 2010, 11:28 AM
  3. Replies: 0
    Last Post: November 3rd 2009, 10:18 AM
  4. Replies: 6
    Last Post: September 12th 2009, 07:23 AM
  5. Finding a point on a line closest to a given point
    Posted in the Pre-Calculus Forum
    Replies: 4
    Last Post: October 6th 2007, 12:21 AM

Search Tags


/mathhelpforum @mathhelpforum