Question 932974
f(x) = -x^2+6x,    x = 0, y-intercept = 0
y = -x^2+6x,    y = 0, x-intercept = 6
....
Completing the Square to obtain Vertex Form
f(x) = -(x-3)^2 + 9
V(-3,9)
..........
the vertex form of a Parabola opening up(a>0) or down(a<0), 
{{{y=a(x-h)^2 +k}}} 
where(h,k) is the vertex  and  x = h  is the Line of Symmetry