Results 1 to 3 of 3

Math Help - Domain of a rational function

  1. #1
    Newbie
    Joined
    Feb 2011
    Posts
    17

    Domain of a rational function

    Hey guys so I'm currently working on a problem:

    A rectangle has area 16 m2. Express the perimeter of the rectangle as a function of the length L of one of its sides.
    I was able to attain the function P(L) which is:

    \frac {2L^2+32}{L}

    My issue comes with the next question which is:

    State the domain of P. (Assume the length of the rectangle is larger than its width. Enter your answer using interval notation.)
    I think it's the wording that has me confused. I'm assuming the answer is -infinity to +infinity with the exclusion of 0. However, I made the assumption that because a rectangle cannot have negative sides I also excluded values less than 0 and input (0,+infinity) as the answer and got it wrong.

    Just wondering if I'm interpreting the question wrong cause I can't seem to get it right.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor
    Joined
    Aug 2007
    From
    USA
    Posts
    3,110
    Thanks
    2

    Re: Domain of a rational function

    You seem to be considering the function on its own merits. This relates to a real rectangle. Put the rectangle back into consideration.

    L > W = 16/L
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Newbie
    Joined
    Feb 2011
    Posts
    17

    Re: Domain of a rational function

    Oh wow, I get it now. I was making it complicated for myself! Anyways, I was able to get the interval which is (4,+infinity). Thank you!
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Domain of a function
    Posted in the Pre-Calculus Forum
    Replies: 1
    Last Post: March 22nd 2011, 03:45 AM
  2. Replies: 2
    Last Post: March 20th 2011, 01:29 AM
  3. Replies: 3
    Last Post: September 14th 2010, 02:46 PM
  4. Determine the domain of a rational function
    Posted in the Pre-Calculus Forum
    Replies: 5
    Last Post: June 30th 2008, 04:56 PM
  5. Domain of Rational Functions
    Posted in the Pre-Calculus Forum
    Replies: 1
    Last Post: January 31st 2007, 05:35 PM

Search Tags


/mathhelpforum @mathhelpforum