Question 464948
  <pre><font face = "Tohoma" size = 4 color = "indigo"><b> 
Hi,
Using the vertex form of a parabola, {{{y=a(x-h)^2 +k}}} where(h,k) is the vertex
f(x) = -x^2+8x+6 | Completing square to put into vertex form
f(x) = -[(x-4)^2-16]+6
f(x) = -(x-4)^2 + 22 |V(4,22), a = -1 <0 ,parabola opens downward, vertex a max Pt
x = 4, line of symmetry
{{{drawing(300,300,   -25,25,-25,25,blue(line(4,25,4,-25))    grid(1),
circle(4, 22,0.4),
graph( 300, 300, -25,25,-25,25,0,  -x^2+8x+6  ))}}}