$\left\{\begin{matrix}a=-\frac{\sqrt{b-z}\sqrt{-2xy+z-b}}{y}\text{; }a=\frac{\sqrt{b-z}\sqrt{-2xy+z-b}}{y}\text{, }&\left(y\neq 0\text{ and }z=xy+b\right)\text{ or }\left(y\neq 0\text{ and }arg(\frac{-xy+z-b}{y})<\pi \text{ and }b\neq z-xy\right)\\a\in \mathrm{C}\text{, }&z=b\text{ and }y=0\end{matrix}\right.$

$b=-y\sqrt{x^{2}-a^{2}}-xy+z$

$b=-y\sqrt{x^{2}-a^{2}}-xy+z$
$|x|\geq |a|$