## Precalculus (6th Edition)

$C$
Subtract $5$ to both sides of the equation to obtain: $x^2=-5$ Take the square root of both sides to obtain: $\sqrt{x^2}=\pm \sqrt{-5} \\x = \pm \sqrt{(-1)5}$ Since $\sqrt{-1}=i$, then the expression above simplifies to $x=\pm i\sqrt5$ Thus, the answer is $C$.