# How do you find the axis of symmetry and vertex point of the function: #y = -x^2 - x + 9#?

##### 2 Answers

Vertex:

Line of symmetry:

#### Explanation:

use

plug

vertex:

on parabolic functions the axis of symmetry is the vertical line where the vertex is, so the equation is:

An alternate way, using the vertex form:

#### Explanation:

We can change the standard form of the equation to the vertex form, which has the general form:

We get there by completing the square (we do that by taking the constant of the

The vertex is given by

The axis of symmetry runs through the vertex vertically and so takes the form of

This can all be seen in the graph:

graph{-x^2-x+9[-3,3,8,10]}

note that I've **adjusted the graph unequally** vertically and horizontally to better show the vertex