Answer
$$-0.25 + 1.20j, \ or, \ -0.25 - 1.20j$$
Work Step by Step
For the equation $2x^2 +x+3= 0$, we use the quadratic formula as follows
$$
x=\frac{-b \pm \sqrt{b^{2}-4 a c}}{2 a},
\\
a=2, \quad b=1, \quad c=3
.$$
That is,
$$
x=\frac{-1\pm \sqrt{1-24}}{2(2) }=-0.25 + 1.20j, \ or, \ -0.25 - 1.20j
.$$
