$$\left. \begin{array} { l } { x y = x ( - 3 ) ^ { 2 } , } \\ { \text { a n \right.$$
$\left\{\begin{matrix}\\x=0\text{, }&\text{unconditionally}\\x\in \mathrm{C}\text{, }&y=9\end{matrix}\right.$
$\left\{\begin{matrix}\\x=0\text{, }&\text{unconditionally}\\x\in \mathrm{R}\text{, }&y=9\end{matrix}\right.$
