Question

What is the axis of symmetry and vertex for the graph `y= 2x ^2 -9`?

Answer 1

Axis of symmetry `->x=0`
Vertex`->(x,y)=(0,9)`

Explanation:

Compare to the standard form:`" "y=ax^2+bx+c`

There is no `bx` term so the function is symmetric about the y-axis

If the equation had been `y=2x^2` then the vertex would have been at `(0,0)`. However, the `-9` lowers the graph by 9 so the vertex is at:

Vertex`->(x,y)=(0,-9)`