optional?
that's not what I said. once again, with a little more clarity ...
1. if the degree of the numerator = degree of the denominator, then divide every term by the highest degree variable.
2. if degree of the numerator > degree of the denominator, then the limit does not exist ... the rational function changes w/o bound.
3. if the degree of the numerator < degree of the denominator, then the limit is 0.
I believe that covers all three possibilities.