Gem følgende kode i en fil med extension .xhtml,
det virker for mig. Det skulle vise en vandret brøk: a/b
<?xml version="1.0"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1 plus MathML 2.0//EN"
"http://www.w3.org/TR/MathML2/dtd/xhtml-math11-f.dtd" [
<!ENTITY mathml "http://www.w3.org/1998/Math/MathML">
]>
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>Minimum Document with MathML</title>
</head>
<body>
<p>
<math xmlns="&mathml;">
<mfrac>
<mi id="MI1">a</mi>
<mi id="MI2">b</mi>
</mfrac>
</math>
<br />
</p>
</body>
</html>