So we want to find the vertical asymptotes of the function:

Remember that there's a vertical asymptote at points of x where the denominator of the rational function is 0.
So, equal the denominator to zero:

And solve this equation for x as follows:
We could factor

Now, notice that any of both factors could be zero, so:

Therefore, the function has vertical asymptotes at x=6 and x=3.