Resposta :
[tex]f(x)=x^2-2x-3 \\
\Delta=(-2)^2-4.1.(-3)=4+12=16 \\
x=\frac{2+-\sqrt{16}}{2}=\frac{2+-4}{2} \\
\boxed{S=\{-1,3 \}}
\\
x_V=\frac{-b}{2a} \
\\
\boxed{x_V=\frac{2}{4}=\frac{1}{2}} \\
\\
\boxed{y_V=\frac{- \Delta}{4a}=\frac{-16}{4}=-4}[/tex]