To solve the equation \( x^2 + 4 = 0 \), we can rearrange it as follows:
\[ x^2 = -4 \]
Taking the square root of both sides gives:
\[ x = \pm \sqrt{-4} \]
This simplifies to:
\[ x = \pm 2i \]
where \( i \) is the imaginary unit.
Since the solutions involve the imaginary unit \( i \), the types of solutions for \( x \) in the equation \( x^2 + 4 = 0 \) are:
imaginary.