Properties of the Graph of a Quadratic Function Parabola opens up if a > 0; the vertex is a minimum point. Parabola opens down if a < 0; the vertex is a maximum point.
a > 0 Opens up Vertex is lowest point Axis of symmetry Graphs of a quadratic function f(x) = ax 2 + bx + c a < 0 Opens down Vertex is highest point Axis of symmetry
Steps for Graphing a Quadratic Function by Hand Determine the vertex. Determine the axis of symmetry. Determine the y-intercept, f(0). Determine how many x-intercepts the graph has. If there are no x-intercepts determine another point from the y-intercept using the axis of symmetry. Graph.
Without graphing, locate the vertex and find the axis of symmetry of the following parabola. Does it open up or down? Vertex: Since -3 < 0 the parabola opens down.