2. Select the command (c) window, and you can see that it is divided into two parts: category and command.
3. Click the fourth item "Insert" in the category, and then look for "Formula Editor with root number A (written by mathematical method)" in the "Commands" on the right, which is the lower one among all commands.
4. After finding it, press the left key and drag it to the toolbar. When dragging, you can see a small box in the lower right corner of the mouse. If there is a plus sign in it, it means you can put it in this position.
5. After being put into the toolbar, it is a small symbol with the root number A. Click it to add a mathematical formula to the article.