<p>I have to note that MathML support is available in Firefox 4b2. And while syntax does seem quite cumbersome:</p>

<pre><code>&lt;math&gt;
  &lt;mi&gt;x&lt;/mi&gt;

  &lt;mo&gt;=&lt;/mo&gt;
  &lt;mfrac&gt;
    &lt;mrow&gt;
      &lt;mo&gt;&amp;minus;&lt;/mo&gt;
      &lt;mi&gt;b&lt;/mi&gt;
      &lt;mo&gt;&amp;PlusMinus;&lt;/mo&gt;
      &lt;msqrt&gt;
        &lt;msup&gt;

          &lt;mi&gt;b&lt;/mi&gt;
          &lt;mn&gt;2&lt;/mn&gt;
        &lt;/msup&gt;
        &lt;mo&gt;&amp;minus;&lt;/mo&gt;
        &lt;mn&gt;4&lt;/mn&gt;
        &lt;mo&gt;&amp;InvisibleTimes;&lt;/mo&gt;
        &lt;mi&gt;a&lt;/mi&gt;

        &lt;mo&gt;&amp;InvisibleTimes;&lt;/mo&gt;
        &lt;mi&gt;c&lt;/mi&gt;
      &lt;/msqrt&gt;
    &lt;/mrow&gt;
    &lt;mrow&gt;
      &lt;mn&gt;2&lt;/mn&gt;
      &lt;mo&gt;&amp;InvisibleTimes;&lt;/mo&gt;
      &lt;mi&gt;a&lt;/mi&gt;

    &lt;/mrow&gt;
  &lt;/mfrac&gt;
&lt;/math&gt;
</code></pre>

<p>It could be great if we could be allowed this tags.</p>


  x
  =
  
    
      &minus;
      b
      &PlusMinus;
      
        
          b
          2
        
        &minus;
        4
        &InvisibleTimes;
        a
        &InvisibleTimes;
        c
      
    
    
      2
      &InvisibleTimes;
      a
    
  

