Question 814590
  <pre><font face = "Tohoma" size = 3 color = "indigo"><b> 
Hi, 
See highlighted
Note: the vertex form of a parabola is, {{{y=a(x-h)^2 +k}}} 
where(h,k) is the vertex
F(x)=x^2-2x-3    |Completing the Square
F(x)=(x-1)^2 -1 - 3
F(x)=(x-1)^2 - 4    {{{highlight(V(1,-4))}}} and If x = 0  then y = -3
If (x-1)^2 - 4 = 0 , x = 1  ±{{{sqrt(4)}}}= 1  ± 2   , x =  -1, 3
{{{drawing(300,300,   -6, 6, -6, 6,  blue(line(1,6,1,-6))  , grid(1),
circle(1,-4,0.3),
circle(-1, 0,0.3),
circle(3, 0,0.3),
circle(0, -3,0.3),
graph( 300, 300, -6, 6, -6, 6,0,x^2-2x-3   ))}}}