Answer
$$x=-2,\:x=\frac{7}{3}$$
Work Step by Step
A rational expression is undefined when the denominator is equal to zero. Thus, we set the denominator equal to zero to find:
$$ 3x^2-x-14=0 \\ 3x\left(x+2\right)-7\left(x+2\right)=0 \\ \left(x+2\right)\left(3x-7\right)=0 \\ x=-2,\:x=\frac{7}{3}$$