title: Why does matplotlib not show specific math text
body: <p>I'm trying to write a title that looks like this:</p>
  <p><code>plt.title(f'Title \n $\mu=1$')</code></p>
  <p><a href="https://i.stack.imgur.com/u7tWG.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/u7tWG.png" alt="title 1" /></a></p>
  <p><strong>But instead with &quot;mu&quot; I want to use Beta.</strong></p>
  <p><code>plt.title(f'Title \n $\beta=1$')</code></p>
  <p><strong>And gives me this error:</strong></p>
  <p><code>ValueError:  eta=1$ ^ Expected end of text, found '$'  (at char 1), (line:1, col:2)</code></p>
  <p>I have read the docs (<a href="https://matplotlib.org/3.1.1/tutorials/text/mathtext.html" rel="nofollow noreferrer">https://matplotlib.org/3.1.1/tutorials/text/mathtext.html</a>) and:</p>
  <p><code>plt.title(r'$\alpha &gt; \beta$')</code></p>
  <p>Should work, any idea why it doesn't?</p>