Falco Graph Builder is a totally free mathematical tool, that lets you draw mathematic graphs in the axis from the parameters you give.
The process is very easy, just insert the parameters in the Falco Graph Builder command line, and the graphic representation on the axis will automatically appear.
Falco Graph Builder is, above all, a very interesting tool for students, so that, in such a friendly way, they can make their tests and see the different behaviours of the graph depending on each of the given parameters.