I'm trying to add some math formula using LaTeX on the math part of my site, http://onlinemathbiz.com/linear-algebra/. I've already installed MathJax, and I can see it from my settings. However, when I try to edit the above site with Elemenator, I'm having problem to display the math.

Here's what I've tried: I went on to edite it with Elementor, then first selected the widget "Text Editor" and then "custom HTML", and tried typing the following:

$\sqrt(2)$

[math] \sqrt(2) [/math]

...but noen of them worked. I looked up on the internet, and I see that from here - https://docs.mathjax.org/en/stable/platforms/wordpress.html, we need to go to Appearences --> Editor (it doesn't exist anymore, I guess now it's called Theme Editor) ---> go to the drop down list "Theme Files" ---> select "header.php". And then right before the end of the tag, we should insert

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

And doing so would "enable" MathJax with both TeX and MathML input. But I'm too scared to change the header.php, just in case it breaks my site. Is there a simoler solution? It's important to note here that, I'm not making a post with math symbols in it, rather, I'm writing on http://onlinemathbiz.com/linear-algebra/.

I'd really appreciate a step by step answer with examples! Thanks in advance!!