Answer
is a solution
Work Step by Step
Substituting $x$ with $2i$ in given equation, $
x^2+4=0
,$ then
\begin{array}{l}\require{cancel}
(2i)^2+4=0
\\\\
4i^2+4=0
\\\\
4(-1)+4=0
\\\\
-4+4=0
\\\\
0=0
\text{ (TRUE)}
.\end{array}
Since the solution above ended with a TRUE statement, then $2i$ $\text{
is a solution
}$ to the given equation.