Describing Quadratic Functions

To identify the vertex, axis of symmetry, and the absolute maximum or minimum value of the given parabola, let's start by labeling these features on our graph.

We can see above that the vertex is the point $(0,\text{-}4).$ Since the parabola opens upwards, it has a minimum value that is reached at the vertex. Thus, the minimum value is $y=\text{-}4.$ Finally, the axis of symmetry is the vertical line through the vertex. In this case, the equation for the axis of symmetry is $x=0.$