How do you find a vertical asymptote of denominator (2x^2-x-6)?

Find the two zeros of that quadratic. Then evaluate the numerator at each of those x-values. If the numerator is nonzero at either one, you're looking at a vert asymptote at that x-val.

(I'm assuming from your description that the expression you gave is the denominator of a rational function. If not, all bets are off and you'll need to check back in with more details.)

Good luck with it.