Question 430636
Solution: {{{f(x)=-(x+9)^2-4}}}, is a downward parabola with vertex (9,-4).

x=9 is the axis of symmetry and the value y=-4 is the maximum value of f(x).

{{{graph(400, 400, -2, 20, -90, 2, -x^2+18x-85)}}}