$$\left. \begin{array} { l } { y = 2 x ^ { 2 } } \end{array} \right.$$
$x=-\frac{\sqrt{2y}}{2}$
$x=\frac{\sqrt{2y}}{2}$
$x=\frac{\sqrt{2y}}{2}$
$x=-\frac{\sqrt{2y}}{2}\text{, }y\geq 0$
