Question 853115
completing the Square:
y = -x2 + 6x - 7 = -(x-3)^2 + 9 - 7
 y = -(x-3)^2 + 2 is a parabola opening downward from V(3,2), it max point
{{{drawing(300,300,   -6, 6, -6, 6, grid(1), blue(line(3,6,3,-6)) ,
circle(3, 2,0.2),
graph( 300, 300, -6, 6, -6, 6, 0 ,-(x-3)^2 + 2 ) )}}}