$$y=3 { x }^{ 2 }$$
$x=-\frac{\sqrt{3y}}{3}$
$x=\frac{\sqrt{3y}}{3}$
$x=\frac{\sqrt{3y}}{3}$
$x=-\frac{\sqrt{3y}}{3}\text{, }y\geq 0$
$y=3x^{2}$
