Historically including equations on a web page has been a pain. The simplest and best approach was often to just create an image graphic of the equation using something like LaTeXiT. This was far from ideal, especially when you wanted to insert an equation or symbol within text. Happily there is now a mature, well supported, solution: MathJax.

MathJax is an open source Javascript display engine for mathematics that works in all browsers. **No** plugins, **no** special setup or font installations required! With MathJax you define your equations using TeX, MathML or AsciiMath. Wrapped in MathJax Javascript encoded equations are scaled and rendered. MathJax can be used either by pointing to the latest version on the Web, or locally installed on your web server or WordPress. For more about MathJax visit: http://www.mathjax.org

This html

displays this