Set Up MathJax

Include this text somewhere in your document. MathJax recommends to placing it in the HTML header, but it may also appear in the body of the document.

<script type="text/javascript" async 
  src="https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.5/latest.js?config=TeX-MML-AM_CHTML">
</script>

For comprehensive documentation see the MathJax website

Default TeX

The default delimiters for TeX-style mathematics are a combination backslash-parentheses, backslash-square brackets, or double-dollar signs.

In the Markdown text you need to escape the backslashes used for the delimiters.

When \\(a \ne 0\\), there are two solutions to \\(ax^2 + bx + c = 0\\) and they are
\\[x = {-b \pm \sqrt{b^2-4ac} \over 2a}.\\]

Becomes this output:

When \(a \ne 0\), there are two solutions to \(ax^2 + bx + c = 0\) and they are \[x = {-b \pm \sqrt{b^2-4ac} \over 2a}.\]