this is a parabola, first, locate the line of symmetry.
the line of symmetry is x=-b/2a
in this case, b=-2, a=-1, so the line of symmetry is x=-1
when x=-1, f(x)=-(-1)²-2(-1)-3=-2
locate the point (-1,-2) on the grid. this point is the vertex.
get two pairs of points with x=-1 as the symmetry line:
(0, -3) and (-2, -3); (1,-6) and (-3,-6)
connect these five points into a parabola, stick out at the ends because it will extend forever downward.
