To determine if a vertex is a maximum or minimum given the direction of opening the parabola, we have:
If the parabola is open upward as follows:
The vertex represents a minimum.
On the contrary, if the parabola opens downward, we have that the parabola has a maximum:
We can also find if a quadratic equation has a maximum or a minimum if we observe the quadratic coefficient of the quadratic equation:
1. If the quadratic coefficient is negative, we have a maximum.
2. If the quadratic coefficient is positive, we have a minimum.
That is: