You can put this solution on YOUR website! The horizontal asymptotes of occur when or are defined (this is just the formal way of saying that when x gets really large, the value of y is a finite number).
In this case, since the degree in the denominator is larger, and . Since the expression converges, we can add three to each limit and obtain 3 as our horizontal asymptotes. We can check by graphing the function, if we wish: