Method 1: Use the formula editor that comes with WORD (open method: select "Microsoft Formula 3.0" from the menu bar Insert-Object-New). After opening Microsoft Formula 3.0, you can use the tools inside to enter the corresponding formula expression. Usage: By default, formulas take up a lot of space between lines, which makes the document layout unattractive. You can set the layout to "float above the text" just like adjusting a word picture (method: select-right click-format the object-select "float above the text" for the layout), and then you can place it at will. If you want to resize, select Select, and then drag the diagonal handle of the formula to resize the period.

Method 2: Download and install a Mathtype plug-in, and then a Mathtype tool will be added to the toolbar in WORD to input formulas.