$$4x2-12xy+9y2=0$$
$\left\{\begin{matrix}x=\frac{4x_{2}+9y_{2}}{12y}\text{, }&y\neq 0\\x\in \mathrm{C}\text{, }&x_{2}=-\frac{9y_{2}}{4}\text{ and }y=0\end{matrix}\right.$
$\left\{\begin{matrix}x=\frac{4x_{2}+9y_{2}}{12y}\text{, }&y\neq 0\\x\in \mathrm{R}\text{, }&x_{2}=-\frac{9y_{2}}{4}\text{ and }y=0\end{matrix}\right.$
$x_{2}=3xy-\frac{9y_{2}}{4}$