we know that
The formula to solve a quadratic equation of the form [tex]ax^{2} +bx+c=0[/tex] is equal to
[tex]x=\frac{-b(+/-)\sqrt{b^{2}-4ac}} {2a}[/tex]
the discriminant is equal to [tex]{b^{2}-4ac[/tex]
in this problem we have
[tex]-3=-x^{2} +2x[/tex]
[tex]x^{2}-2x-3=0[/tex]
so
[tex]a=1\\b=-2\\c=-3[/tex]
substitute the values
[tex]{(-2)^{2}-4(1)(-3)=4+12=16[/tex]
therefore
the answer is
[tex]16[/tex]
