Answer
$\pm2i,-3,\frac{1}{2}$
Work Step by Step
Step 1. Given a zero $x=-2i$, we know another zero is $x=2i$, thus $(x+2i)(x-2i)=x^2+4$ is a factor.
Step 2. Perform a division as shown in the figure to get the quotient $2x^2+5x-3$ (one can also perform synthetic divisions to get the same result).
Step 3. Solve $2x^2+5x-3=0$ or $(2x-1)(x+3)=0$ to get $x=-3,\frac{1}{2}$
