Currently, only Firefox can render MathML equations embedded in the HTML code. MathJax is a solution to properly view MathML equations embedded in HTML content in a variety of browsers.
If you have DocBook or DITA content that has embedded MathML equations and you want to properly view the equations in published HTML output types (WebHelp, CHM, EPUB, etc.), you need to add a reference to the MathJax script in the head of all HTML files that have the equation embedded.
<script type="text/javascript" src="http://cdn.mathjax.org/mathjax/latest/MathJax.js?config=TeX-AMS-MML_HTMLorMML"> </script>
For DITA documents, you can also edit the DITA Map WebHelp transformation scenario and set the args.hdf parameter to point to the footer.html resource. Then transform to WebHelp and the equation should be properly rendered in the browsers such as IE, Chrome, and Firefox.