Results 1 to 2 of 2

Math Help - Graphing ln help

  1. #1
    Newbie
    Joined
    Mar 2013
    From
    Adelaide
    Posts
    1

    Graphing ln help

    Hallo

    Im a bit stuck.

    I need to graph the function f(x) = ln(9-x^2) to find domain and range.
    I assumed x > 3 as cant take ln of 0 or negative number. My graph came out looking like a nike tick.

    However, when i checked my answer on graphics calculator, the graph is a u-shaped! with some negative values!
    Im very confused. How do i get the right answer?

    Thank you for your time.

    LINK: graph of ln(9-x^2) ln(9-x^2) - Wolfram|Alpha
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor
    Joined
    Sep 2012
    From
    Australia
    Posts
    3,668
    Thanks
    608

    Re: Graphing ln help

    Hey razzatazz.

    When we look at the domain, we typically look at the region where the input to the mapping (or function) is defined.

    Now logarithms are only defined when the input is > 0 so this means that 9 - x^2 > 0 or x^2 < 9 which means x > -3 and x < 3.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. SAS graphing help
    Posted in the Math Software Forum
    Replies: 1
    Last Post: January 27th 2011, 02:10 AM
  2. Graphing
    Posted in the Calculus Forum
    Replies: 1
    Last Post: May 18th 2010, 02:08 PM
  3. Graphing
    Posted in the Pre-Calculus Forum
    Replies: 1
    Last Post: August 20th 2008, 05:47 PM
  4. graphing
    Posted in the Pre-Calculus Forum
    Replies: 1
    Last Post: August 11th 2008, 11:34 PM
  5. graphing log
    Posted in the Pre-Calculus Forum
    Replies: 2
    Last Post: August 26th 2007, 07:22 AM

Search Tags


/mathhelpforum @mathhelpforum