The graph of a rational function $f$ is shown below. Determine the vertical asymptotes of $f$. If there is more than one, enter your answer as a comma-separated lis $x=$ Preview

Step 1 ：The vertical asymptotes of a function are the values of x for which the function approaches infinity or negative infinity. These are the values of x for which the denominator of the function is zero, but the numerator is not zero.

Step 2 ：In the graph, these are the x-values where the graph goes off to infinity or negative infinity.

Step 3 ：Without the graph, it is impossible to determine the vertical asymptotes.