where a, b, and c are real numbers and a ≠ 0 .
The quadratic term is ax
2
, the linear term is
bx, and the constant term is c. Quadratic
functions have degree two. The graph of a
quadratic function is called a parabola. If
a < 0, then the parabola opens downward,
like function g. If
a > 0, then the parabola
opens upward like function f. If
the parabola opens upward, then
the vertex is the point whose yvalue
is the minimum value of f.
If the parabola opens downward,
then the vertex is the point
whose y-value is the maximum
value of f. The vertical line that
goes through the vertex is called
the axis of symmetry of the
parabola.
