y = -x2 + 4x - 3

[tex]d = {4}^{2} - 4 \times ( - 1) \times ( - 3) = 16 - 12 = 4 \\ x = \frac{ - 4 + 2}{ - 2} = \frac{ - 2}{ - 2} = 1 \\ x = \frac{ - 4 - 2}{ - 2} = \frac{ - 6}{ - 2} = 3[/tex]