LaTeX Formulas
You can put LaTeX formulas into your postings by using the [tex] tag. For example
[tex]x=\frac{-b\pm\sqrt{b^2-4ac}}{2a}[/tex] yields

For a list of possibilities, see the mimetex tutorial.

This was however the old way, the new way is via mathjax. Put the LaTex code between \\( and \\)