The given quadratic equation is:
[tex]x^2+2=0[/tex]Subtract 2 from both sides
[tex]\begin{gathered} x^2+2-2=0-2 \\ x^2=\text{ -2} \end{gathered}[/tex]Find the square root of both sides
[tex]\begin{gathered} \sqrt[]{x^2}=\text{ }\sqrt[]{-2} \\ x=\sqrt[]{-2} \\ x=\pm\sqrt[]{2}\times\sqrt[]{-1} \\ x\text{ =}\pm\text{ }\sqrt[]{2}i \\ x\text{ = }\pm i\sqrt[]{2} \end{gathered}[/tex][tex]\begin{gathered} x\text{ = }-i\sqrt[]{2}\text{ or i}\sqrt[]{2} \\ \end{gathered}[/tex]