Final answer:
At x=3, the rational function f(x)=(x+2)/(x^2-x-6) has a vertical asymptote due to the denominator becoming zero. This causes the function to become undefined.
Step-by-step explanation:
At x=3, the rational function f(x)=(x+2)/(x^2-x-6) has a vertical asymptote at x=3. This means that the graph of the function approaches positive or negative infinity as x approaches 3 from the left or right side, respectively. The reason for this is that the denominator of the rational function, x^2-x-6, becomes zero when x=3, which results in an undefined value for the function.