The new federal income tax, signed into law on 22 October 1986, spurred extensive analysis in the daily newspapers, an analysis similar to the study of a function in a beginning mathematics course. This similarity with the familiar income tax may help students understand three aspects of the abstract concept of “function”: formulas, graphs, and ordered pairs. Defined by several formulas—not just one—the tax function also prepares beginners for such functions as the a bsolute value, which also involves both a lgebraic formulas and logical tests, a combination that poses difficulties to many students (see Johnson [1986]).
