Ms Burton, I learned this chapter on Youtube by myself. And I took some notes.
The vertex of a parabola is its highest or lowest point.(_,_) The vertex may be a maximum or minimum point.
If the graph opens up, x should be positive, the vertex amy be the minimum point, the domain can be any real numbers, and the range must be y>= (greater than the vertex)
If the graph opens down,x should be negative, the vertex amy be the maximum point, the domain still can be any real numbers, and the range must be y<= (lease than the vertex)