Answer
The solution set is $\color{blue}{\left\{-\frac{1}{2}, 3\right\}}$.
Work Step by Step
Factor the trinomial:
$(2x+1)(x-3)=0$
Equate each factor to $0$:
$2x+1 = 0 \text{ or } x-3=0$
Solve each equation above :
$2x+1 = 0
\\2x+1-1=0-1
\\2x=-1
\\x =-\frac{1}{2}$
or
$x-3+3=0+3
\\x=3$
Thus, the solution set is $\color{blue}{\left\{-\frac{1}{2}, 3\right\}}$.