Unfortunately, if you want to use the JSXGraph filter, the new TinyMCE text editor won't let you. ⁠

To be able to create different graphs you need to use a specific syntax, similar to this:

<jsxgraph>

    var brd = JXG.JSXGraph.initBoard(BOARDID, {boundingbox:[-5,5,5,-5], axis:true});
    var p = brd.create('point', [1,2]);
</jsxgraph>

Unfortunately Tiny removes the crucial <jsxgraph> tags and replaces them with <p>. So you will see the code as a text rather than the generated graph.

https://moodle.org/plugins/filter_jsxgraph