Latex Problem

I am new to hugo.
I have added MathJax in my site using the following code,

{{ if or (and (isset .Site.Params "math") (eq .Site.Params.math true)) (and (isset .Params "math") (eq .Params.math true)) }}
<script type="text/x-mathjax-config">
  MathJax.Hub.Config({ tex2jax: { inlineMath: [['$','$'], ['\\(','\\)']] } });
</script>
<script async src="{{ .Site.BaseURL }}js/MathJax/MathJax.js?config=TeX-AMS_CHTML"></script>
{{ end }}

Then in my *.md file, I write like this,

$ a =   a_{0} \\ a_{15} \\ a_{16}  $

$ a =   a_{0} $

$ a =   a_{0} \\ a_{1} $

$ a =   a_0 a_1 a_2 a_3  $

$ a =   a_0 \\ a_1 \\ a_2 \\ a_3  $

$ \frac{1}{2}_{2}^{3} $

which gives the following output.

Why the code haven’t compiled?
1.When multiple a_{} notation is used.
2. Why there is no new line when using \

1

Note: This codes are successfully compiled in the live demo of MathJax site.

I’m not especially familiar with Mathjax, but have you read the docs and the “Issues with Markdown” page section: