$$y = x ^ { 2 } - 4 x + 5$$
$x=\sqrt{y-1}+2$
$x=-\sqrt{y-1}+2$
$x=\sqrt{y-1}+2$
$x=-\sqrt{y-1}+2\text{, }y\geq 1$
$y=x^{2}-4x+5$
