I have included the following on my html page:
I was getting the same error as you did with your code.
If you download jqMath and open the COPY_ME.html
in the downloaded folder, you should be able to see the structure of the html
and how to make changes to it. Everything works fine there.
The example provided on jqMath official website uses jQuery 1.4.3 and your example uses jQuery 1.12.1, I am not sure but that could be the issue.
I hope this helps.