TeX is a typesetting standard that, among other things, allows you to typeset complex math formulas. One flavor of Tex is LaTeX, for which LaTeXiT serves as a front-end for on Mac OS X. Using LaTeXiT, ...

Do you need to calculate the rate at which something changes over time? Whether it's the change in the x-value over the change in the y-value of a line on a graph, or the distance travelled by a car ...