Answer
$6, \ or, \ -0.667$
Work Step by Step
For the equation $3x^2 -16x-12= 0$, we use the quadratic formula as follows
$$
x=\frac{-b \pm \sqrt{b^{2}-4 a c}}{2 a},
\\
a=3, \quad b=-16, \quad c=-12
.$$
That is,
$$
x=\frac{16\pm \sqrt{16^2-4(3)(-12)}}{2(3) }=6, \ or, \ -0.667
.$$
