decide whether to use factoring, square roots, or completing the square to solve the equation

According to the given equation, to solve the equation we have to use the square roots:
[tex]\begin{gathered} (x-7)^2=-9 \\ x-7=\sqrt[]{-9} \\ x-7=\pm3i \\ x=7\pm3i \\ x1=7+3i \\ x2=7-3i \end{gathered}[/tex]