Answer
$2.12, \ or, \ -0.787$
Work Step by Step
For the equation $3x^2 -4x-5 = 0$, we use the quadratic formula as follows
$$ x=\frac{-b \pm \sqrt{b^{2}-4 a c}}{2 a}, \\
a=3, \quad b=-4, \quad c=-5.$$
That is,
$$ x=\frac{4 \pm \sqrt{16+60}}{2(3) }=2.12, \ or, \ -0.787
.$$
