$$\left. \begin{array} { l } { x ^ { 2 } + ( 1 - k ) x + k - 3 = 0 } \end{array} \right.$$
$x=\frac{\sqrt{k^{2}-6k+13}+k-1}{2}$
$x=\frac{-\sqrt{k^{2}-6k+13}+k-1}{2}$
