When \(a \ne 0\), there are two solutions to \(ax^2 + bx + c = 0\) and they are
\[x_1 = {-b + \sqrt{b^2-4ac} \over 2a}\] \[x_2 = {-b - \sqrt{b^2-4ac} \over 2a} \notag\]You need set mathjax: true in the _config.yml or the markdown’s front matter to enable it.
After MathJax enabled, you can set mathjax_autoNumber: true to have equations be numbered automatically, You can use \notag or \nonumber to prevent individual equations from being numbered.
markdown:
When $$a \ne 0$$, there are two solutions to $$ax^2 + bx + c = 0$$ and they are
$$x_1 = {-b + \sqrt{b^2-4ac} \over 2a}$$
$$x_2 = {-b - \sqrt{b^2-4ac} \over 2a} \notag$$