Question 399550
  <pre><font size = 3 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 + 6x + 1    |completing the square
f(x) = -[(x-3)^2 - 9] + 1 
f(x) = -(x-3)^2 +10  vertex is Pt(3,10) Line of symmetry  x= 3

{{{drawing(300,300, -10,10,-10,10,blue(line(3,10,3,-10)) ,  
 grid(1),
circle(3, 10,0.4),
graph( 300, 300, -10,10,-10,10,-x^2 + 6x + 1))}}}