Answer:
(see attached file)
vertex: (-4, 23)
axis of symmetry: x = -4
Step-by-step explanation:
The axis of symmetry always passes through the vertex of the parabola. The x -coordinate of the vertex is the equation of the axis of symmetry of the parabola.
(i'm not the best at explaining things, but khan academy has some amazing math resources if you want to check it out)