As you’ve seen, GraphLib is an easy-to-use library for graphing functions, plotting data points, and drawing line graphs. This library is freely available, and you can get the source code for it ...

Worked examples The graph below has a turning point (3, -2). Write down the nature of the turning point and the equation of the axis of symmetry.

The graph of the quadratic function y = a x 2 + b x + c has a minimum turning point when a> 0 and a maximum turning point when a a <0. The turning point lies on the line of symmetry.

Ivan Baggs, Functions with a Closed Graph, Proceedings of the American Mathematical Society, Vol. 43, No. 2 (Apr., 1974), pp. 439-442 ...