How do you find the vertex of a quadratic equation #y= -x^2 + 9#?

1 Answer
Jun 9, 2016

Answer:

Vertex at: #(0,9)#

Explanation:

The general explicit vertex form is
#color(white)("XXX")y=color(green)(m)(x-color(red)(a))^2+color(blue)(b)#
for a parabola with vertex at #(color(red)(a),color(blue)(b))#

The given equation: #y=-x^2+9#
can be converted into the explicit vertex form as
#color(white)("XXX")y=color(green)(""(-1))(x-color(red)(0))^2+color(blue)(9)#
for a parabola with vertex at #(color(red)(0),color(blue)(9))#

For verification purposes, here is the graph of the original equation:
graph{-x^2+9 [-12.96, 12.35, -2.49, 10.17]}