The green dotted line represents the Axis of Symmetry. This represents a non-existent line that cuts the parabola into two symmetrical halves.
A positive parabola will have a minimum.
The green dotted line represents the Axis of Symmetry. This represents a non-existent line that cuts the parabola into two symmetrical halves.
A negative parabola will have a maximum.
Zeros will be the x value(s) when the parabola crosses/touches the x-axis.
There can be zero, one, or two zeros of a quadratic function.
This chart, as seen on the 9-1 page, gives information on how to find the vertex, line of symmetry among other basic characteristics of quadratic functions.