<p>Problem:</p>

<p><a href="https://stats.stackexchange.com/questions/212581/unbiasedness-of-the-ols-estimators">This question</a> has MathJax $\beta$'s in it. They're rendering as $?$'s for me. ($\hat{?}$ amuses me in particular -- it tickles my funny bone for some reason):</p>

<p><a href="https://i.stack.imgur.com/2xLp8.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/2xLp8.png" alt="enter image description here"></a></p>

<p>Note that the rest of the MathJax is fine there.</p>
