Math Video - Graphs of Quadratic Functions
This video shows the use of an applet to explain the effects of parameters a, b and c included in the definition of a quadratic function of the form
f(x) = a x 2 + b x + c
on the properties of graph, which is a parabola, of the function such opening up or down, the vertex and the range of values.
More may be found at Math Videos From Analyzemath