Ok, so in order to find the line of symmetry, let's compare the parabola with have with the theory.
When we have a general parabola
[tex]\begin{gathered} y=a{{(x-h)}^2}-k \\ y=-2(x-3)^{2}-(+4) \end{gathered}[/tex]
The theory states that the symmetry lies on x = k
So, the line of symmetry is x=4
