How to insert mathmatics or equation into Markdown

MathJax plugin

MathJax plugin is a very easy and powerful tool for implementing HTML. Add MathJax CDN via below syntax:

<script type="text/javascript"
   src="http://cdn.mathjax.org/mathjax/latest/MathJax.js?config=TeX-AMS-MML_HTMLorMML">
</script>

[//]: <> (Markdown annotation style: the link for callinf online MathJax function, you can also download it and use it offline)

Now, it can works. 

1. formula between lines

$$ a+b=c $$

2. formula within lines

$$ evidence\_{i}=\sum \_{j}W\_{ij}x\{j}+b\_{i} $$ （1.1）            

\\ (W\_i \\) and \\ (i \\) （1.2）

The difference of 1.1 and 1.2. Testing it.

Appendix: Online equation convert tex tool - [WebEqution](https://webdemo.myscript.com/#/demo/equation)