<p>I had set my preferences to use MathML, but I've just realised it fails to display square root of fractions correctly. With MathML, 
$$\sqrt{\frac{n-2}{1-r^2}}$$
looks almost the same as
$$\frac{ \sqrt{n-2}}{1-r^2}$$
In particular, the square-root encloses only the numerator, which changes the interpretation of the formula</p>

<p>I'm using Firefox 3.6.10 under Windows XP Pro Service Pack 3. I selected MathML by right-clicking any displayed formula to display a context menu and selecting Settings => Math Renderer => MathML.</p>

<p>Apologies if this is a MathML problem rather than a StackExchange problem. I don't know where to raise MathML bugs though.</p>

<p>EDIT: Snip of screenshot as requested:
<img src="https://i.stack.imgur.com/t0teJ.png" alt="wrongly displayed square-root of fraction under MathML"></p>
