Thanks for the details. I am not a linux guy nor moodle. Trying to learn Could you kindly elaborate followings and help me how to check please?
2) the fact that the dollar signs are in the text but are parsed out means that the filter is parsing the signs, but perhaps is unable to display the image. This is typically not a result system installed TeX or ImageMagick, but with mimetex perms and improper paths to Tex, so check your other debug tests to see what your perms returns are.
3) You said you tried to do a new install of TexLive, but you did not discuss where you installed it. Did you double check your new install and adjust the paths to your binaries?
I just run MIchael's command and assumed that was enough. sudo apt-get install texlive-full
So how should I check and correct?
4) Do you have command line access? If you do, check man pages for each of the three binaries and make sure they are executable by your web daemon
Again I stuck at the how to!