\documenttype[mathml-altheim]{html}
% Locate gellmu.el as "http://www.albany.edu/~hammond/gellmu/gellmu.el"
% Use: "emacs -batch -l gellmu.el -f gellmu-xml whatever.glm" to make
% "whatever.xml".  Then view "whatever.xml" with MathML-enabled Mozilla.
% The "mathml-altheim" \documenttype option sets up the Carlisle/Altheim
%   XHTML 1.1 plus MathML 2.0 unified document type definition.
%
\newcommand{\mns}{xmlns="http://www.w3.org/1998/Math/MathML"}
\newcommand{\imath}[1]{\math[\mns]{\mrow{#1}}}
\newcommand{\drmath}[1]{\math[\mns class="display" mode="display"]{\mrow{#1}}}
\newcommand{\plus}{\mo{+}}
\newcommand{\minus}{\mo{-}}
\newcommand{\pm}{\mo{±}}
\newcommand{\mul}{\mo{ }}
\newcommand{\eqn}[2]{\mrow{#1}\mo{=}\mrow{#2}}
\newcommand{\bal}[1]{\mfenced{\mrow{#1}}}
\newcommand{\frac}[2]{\mfrac{\mrow{#1}\mrow{#2}}}
\begin{head}
\style[type="text/css"]{
body {
  html,background: #fff;
  color: black;
  background-color: white;
}

h1 {
  display: block;
  margin-left: auto;
  margin-right: auto;  
  text-align: center;
}


.display {
  display: block;
  margin-left: auto;
  margin-right: auto;
  text-align: center;
}
}
\title{A MathML Example: The “Quadratic Formula”}
\end{head}
\begin{body}
\h1{A MathML Example: The “Quadratic Formula”}
\h2[class="display"]{William F. Hammond}

\p{
This is an XHTML document with MathML markup prepared using the basic
layer of GELLMU and the XML namespaces regime for extending the basic
tagset of XHTML.
}
\p{The quadratic equation
\imath{\mi{a}\mul\msup{\mi{x}\mi{2}} \plus \mi{b}\mul\mi{x}
             \plus \mi{c} \mo{=} \mi{0}}
has roots}
\drmath{
 \eqn{
     \mi{x}
    }{
     \frac{
 \mo{-}\mi{b} \pm \msqrt{\msup{\mi{b}\mi{2}} \minus \mi{4}\mul\mi{a}\mi{c}}
         }{
 \mi{2}\mul\mi{a}
         }
    }
\mtext{ .}
}
\end{body}