The graph of quadratic equation is a parabola that opens upward or downward.
If a (the coefficient of leading terms) is negative, the parabola opens downward (upside down) and has a maximum vertex.
If a is positive, the parabola opens upward and has a minimum vertex.
We can write the parabola in vertex form:
y = a(x-h)² + k, where the (h,k) is the coordinates of the parabola's vertex.