For anyone interested in creating their own formulas Kerry Mitchell has 2 "creating fractal formula" courses that where created for UF 4 that were $50. You can email him for the links & donate $25 for both of them at lkmitch@gmail.com. They're still compatible with UF5 & cover fractal & coloring formula creation.
Here's an excellent video tutorial for beginners on understanding the math behind the Mandelbrot fractal. Watch it several times to fully understand it.
http://www.mandelbrotset.net/tutorial.html
And if that's not enough to confuse you about fractal math here's some more. Not related to the mandelbrot set specifically though:
http://www.clarku.edu/~djoyce/complex/