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.

Functions The graph of f (x) = x 2 is the same as the graph of y = x 2. Writing graphs as functions in the form f (x) is useful when applying translations and reflections to graphs.

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