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

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Answer 1 · 2016-04-22T20:34:02

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

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 $->(x,y)=(0,-9)$

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