$x=-\sqrt{y^{2}-5}$
$x=\sqrt{y^{2}-5}\text{, }arg(y)<\pi \text{ or }y=0$

$x=\sqrt{y^{2}-5}$
$x=-\sqrt{y^{2}-5}\text{, }y\geq \sqrt{5}$

$y=\sqrt{x^{2}+5}$