Mathematics and scientific notations have historically been difficult to display electronically.
Moodle has a new built-in Equation editor that replaces the old DragMath editor. As you enter TeX equations you can see these appear in the preview at the bottom of the window.
You access the equation editor from the Moodle text editor's equation button 
- you may need to toggle on the full view 'Toolbar toggle' button 
(the top-left button) to see the equation editor button.
There are several other online tools that may help you write Tex equations:
