=- 1/2(X？ -2X+ 1)+ 1/2-2/3
=- 1/2(X- 1)？ - 1/6,
Vertex coordinates (1,-1/6) are in the fourth quadrant.
Open down,
∴ The parabola does not pass through the first quadrant,
The intersection point c of the first quadrant does not exist.