The graph of y = (x^2 - 9)/(x^2 - 5x + 2) has a horizontal asymptote at y = a. What is a?

As the magnitude of x gets very large, both the numerator and the denominator become dominated by the x^{2} term. Hence, in the limit as x tends to either +infinity or -infinity, y tends to x^{2}/x^{2} = 1.