Answer
$x=-\frac{1}{3}$
Work Step by Step
Step 1. Rewrite the equation as $3x^3-2x^2+8x+3=0$, list possible rational real zeros $\frac{p}{q}: \pm1,\pm3,\pm\frac{1}{3}$
Step 2. Use synthetic division as shown in the figure to find zero(s) $x=-\frac{1}{3}$
Step 3. Use the quotient to find other zeros: $3x^2-3x+9=0$, no real solutions.