$${ x }^{ 2 } -px+q=0$$
$\left\{\begin{matrix}p=x+\frac{q}{x}\text{, }&x\neq 0\\p\in \mathrm{C}\text{, }&q=0\text{ and }x=0\end{matrix}\right.$
$\left\{\begin{matrix}p=x+\frac{q}{x}\text{, }&x\neq 0\\p\in \mathrm{R}\text{, }&q=0\text{ and }x=0\end{matrix}\right.$
$q=-x\left(x-p\right)$