1. Open Microsoft Word 20 10 (the version is similar, and the steps are similar), select the insert option in the toolbar above, then click the π-like symbol (formula) on the right, and then select Insert a new formula.

2. Enter lngX= in the inserted new formula first, and then find the formula model selected in the following figure as shown in the following figure.

3. We need to input n- 1 and i= 1 in the upper and lower boxes of this model respectively.

4. Then you need to insert another formula model, as shown below, and insert the radical model shown below in the small box on the right side of the formula.

5. According to the first picture, we also need to insert a model here, as shown in the figure below, and insert an upper subscript model into the radical model.

6. Enter (xi-xi+ 1) in the box below, and enter 2 in the box above to indicate a square. The final result is shown in the figure below.