Explain Why The Parabola Opens Downward

The parabola opens downward. In the quadratic equation of the parabola a will be less than 0 because the parabola opens downward.
My equation for the axis of symmetry is x=4. I found the axis of symmetry by finding the coordinate that divided the parabola into two congruent halves.
The vertex of this graph is, (4,14). I found the vertex by finding the highest or lowest point of the parabola. In this case because the parabola open downward, so it is the highest point that is the vertex.
The function has a maximum value. It has a maximum value because it opens downwards. The maximum value is also the vertex when the parabola opens downward. If the parabola opens upward the minimum value will be the vertex. Also, in the quadratic equation,