Regroup terms.
\[y=3-{x}^{2}\]
Subtract \(3\) from both sides.
\[y-3=-{x}^{2}\]
Multiply both sides by \(-1\).
\[-y+3={x}^{2}\]
Regroup terms.
\[3-y={x}^{2}\]
Take the square root of both sides.
\[\pm \sqrt{3-y}=x\]
Switch sides.
\[x=\pm \sqrt{3-y}\]
x=sqrt(3-y),-sqrt(3-y)
