title: Pandoc: [WARNING] Could not convert TeX math
body: <p>I tried to convert html to docx by using Pandoc: <br/>
  here is my html code:</p>
  
  <pre><code>&lt;p&gt; Example: ${v_1} = {\rm{ }}{v_2}$&lt;/p&gt;
  </code></pre>
  
  <p>with MathJax config in head:</p>
  
  <pre>
  
      MathJax.Hub.Config({
      extensions: ["tex2jax.js", "TeX/AMSmath.js", "TeX/AMSsymbols.js"],
      jax: ["input/TeX", "output/HTML-CSS"],
      tex2jax: {
          inlineMath: [['$', '$'], ["\(", "\)"]],
          displayMath: [['$$', '$$'], ["\[", "\]"]],
      },
      "HTML-CSS": {availableFonts: ["TeX"]}
  });
  
  </pre>
  
  <p>Pandoc command that i used (Pandoc version 2.2.3.2): </p>
  
  <pre>
  
      pandoc -s  test.html --mathjax  -f html+tex_math_dollars   --pdf-engine=xelatex  -o  xxx.docx
  
  </pre>
  
  <p>then i got a warning:</p>
  
  <pre>
  
      [WARNING] Could not convert TeX math '{v_1} = {\rm{ }}{v_2}', rendering as TeX:
        {v_1} = {\rm{ }}{v_2}
                    ^
        unexpected "{"
        expecting "%", "\\label", "\\nonumber" or whitespace
  
  </pre>
  
  <p>Someone please tell me how to fix this. Thanks!</p>