hugo/_vendor/github.com/gohugoio/gohugoioTheme/layouts/partials/math.html

<script id="MathJax-script" async src="https://cdn.jsdelivr.net/npm/mathjax@3/es5/tex-chtml.js"></script>
<script>
  MathJax = {
    tex: {
      displayMath: [['\\[', '\\]'], ['$$', '$$']],  // block
      inlineMath: [['\\(', '\\)']]                  // inline
    }
  };
</script>