# Thread: Domain of a rational function

1. ## 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.

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

3. ## 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!