The correct axis of symmetry is x = -1.
Explanation:
Our equation is
[tex]y=\frac{1}{3}(x+1)^2-3[/tex].
This is in vertex form, which is
y = a(x-h)² + k, where (h, k) is the vertex.
In our equation, h corresponds with -1 and k corresponds with -3, making the vertex (-1, -3).
The axis of symmetry is the x-coordinate of the vertex; this makes the axis of symmetry for this equation x = -1.
