I already completed all the code but i have a problem with my code so I attached

I already completed all the code but i have a problem with my code so I attached

I already completed all the code but i have a problem with my code so I attached a file that shows the points for this code and my problem is when I do the ( 7.1 Example 1) in the attached file. it does not work idk why
need help asap within 2 hours max