Applications involving minimum or maximum It is important to remember that the minimum or maximum of a quadratic function always occurs at the vertex of the parabola. This hint will not be provided on tests! As always, show your work finding your answers. Graphing calculators are a helpful tool, but are not a substitute for a symbolic process. 1. The amount of junk mail received in one week by residents of a suburban town can be modeled by the quadratic function m(x) = -x +30x + 100, where m(x ) is the number of pieces of junk mail (in thousands) and x is the number of years after 1980. a. In what year should the amount of junk mail reach its maximum? b. What is the maximum amount of junk mail