Hi Alex,
I go through the post carefully, we can build a Piece-wise function in Word by
- Click Insert>Equation.
- In Bracket, select the piece-wise function from Example in Common Brackets, and you may edit your equation based on your requirements.
Can you insert the piece-wise function in this way? Or if the equation editor doesn’t work in Word at all? If you cannot edit any equation with the editor, please try run Office online repair and check the result, go to Control Panel>Apps & Features>Find Office>Modify>Online repair, for more information: Repair an Office application - Office Support
If suggestions above doesn’t help, could you please share information below with us for further troubleshooting?
- What is your Office version? could you please share a screenshot on File>Account page with us?
- Did you get error message? or could you please share more details on symptom of the issue with us?
Regards,
Clark