follow these rules
This procedure leads to the following general result:
* 1 * If the degree of the denominator exceeds that of the numerator, y = 0 is a horizontal asymptote;
* 2 * If the leading coefficient of the numerator is a and the leading coefficient of the denominator is b and their degrees are equal then is a horizontal asymptote;
* 3 * If the degree of the numerator exceeds that of the denominator, there is no horizontal asymptote.