This document discusses finding a quintic (5th degree) function to approximate motion data. It explains that while the calculator can do quadratic, cubic, and quartic regression, it cannot do quintic regression. To find the quintic function, six points are needed to create six equations with the six unknown coefficients. The key points chosen are points of extrema (maximums and minimums) and inflection, which are used to set up a system of six equations that can be solved for the coefficients.