Answer:
[tex]y=0[/tex]
Step-by-step explanation:
we know that
The equation in vertex form of a horizontal parabola is equal to
[tex]x=(y-k)^{2} +h[/tex]
where
(h,k) is the vertex
and the axis of symmetry is the y -coordinate of the vertex
so
[tex]y=k[/tex]
In this problem we have
[tex]y^{2}=-8x[/tex] ----> is a horizontal parabola open to the left
The vertex is the origin
therefore
the equation of the axis of symmetry is equal to
[tex]y=0[/tex]
