Question 760907
The only constraint given is that the area fenced should be 2000 square feet.
If this is not supposed to be realistic, x could be any positive real number.
So the domain would be all the positive real numbers.
It could be x=2000 feet, and then you would be fencing an area 1 foot by 2000 feet.
 
We could make x=20,000 feet long and the fenced area width would be 0.1 foot=1.2 inches.
 
As the width gets more ridiculously small, x could get as large as we want.