over and underbrace brace in Tex

Use the Tex code below to generated upper and lower brace

\overbrace{your-formula}^\text{your comment} 
\underbrace{your-formula}_\text{your comment} 

The code below will give this result $$ s = \overbrace{ \underbrace{\sigma}_\text{real} + \underbrace{j\omega}_\text{imaginary} }^\text{complex number}$$

\[
  z = \overbrace{
    \underbrace{x}_\text{real} +
    \underbrace{iy}_\text{imaginary}
   }^\text{complex number}
 \]

Use highlight.js to highlight code on Blogger.com

   Find the template HTML code: Design→Theme→Live on Blog→Edit HTML, then put the codes below just before </head> (use Ctrl+F to find it.)

<link href="//cdnjs.cloudflare.com/ajax/libs/highlight.js/9.11.0/styles/default.min.css" rel="stylesheet"></link>
<script src="//cdnjs.cloudflare.com/ajax/libs/highlight.js/9.11.0/highlight.min.js"></script>
<script>hljs.initHighlightingOnLoad();</script>

  Use the <code>...</code> to highlight code and <pre>...</pre> to make code block.
The updated download location is in https://highlightjs.org/download/

We van use different style of highlight (demo here) by change the file name in the above block. For examplem change default.min.js to github-gist.min.css will make the highlight become githhub gist style.

Use the code below to specifiy the language. the list of supported language is http://highlightjs.readthedocs.io/en/latest/css-classes-reference.html
 

<pre><code class="html">...</code></pre>

Finally, don't forget to escape text to html with online tool such as http://codebeautify.org/html-escape-unescape

Use MathJax to render math formula in Blogger.com

Attention: do not use the dynamic view theme, MathJax does not work on it.
   First find the template HTML code: Design→Theme→Live on Blog→Edit HTML Then put the codes below just before </head> (use Ctrl+F to find it.) The default math delimiters are



• $$...$$ and \[...\] for displayed mathematics,
• \(...\) for in-line mathematics. 

   You may use something like <span>$</span> to isolate the dollar sign so that MathJax will not use it as a delimiter. To always get the latest version javascript, use the recommendation on http://docs.mathjax.org/en/latest/start.html

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

if you want to use single-dollars for in-line math mode as in https://math.stackexchange.com/ , you must enable that explicitly in your configuration:

<script type="text/x-mathjax-config">
MathJax.Hub.Config({
  tex2jax: {inlineMath: [['$','$'], ['\\(','\\)']]}
});
</script>
<script type="text/javascript" async src="path-to-mathjax/MathJax.js?config=TeX-AMS_CHTML"></script>