Quadratic Function Basics
A quadratic function follows the form f(x) = ax² + bx + c, where a, b, and c are constants. Each quadratic creates a parabola when graphed, with several important features to identify.
The vertex is the highest or lowest point on the parabola, found at −b/2a,f(−b/2a). For example, in f(x) = 2x² - 4x + 3, the vertex sits at (1,1). This point tells you where the function reaches its maximum or minimum value.
The axis of symmetry is a vertical line passing through the vertex, dividing the parabola into mirror images. It's always at x = -b/2a. In f(x) = -x² + 6x - 5, the axis of symmetry is x = 3.
💡 Think of a quadratic function like a mirror - the axis of symmetry is where you'd place the mirror to create identical reflections on both sides!
The discriminant D=b2−4ac tells you about the roots of the equation. For f(x) = 3x² + 2x + 1, the discriminant is D = -8, which means this quadratic has no real roots theparabolanevercrossesthex−axis.