taking the derivative and setting equal to zero

10:19

4:21

7:12

21:16

1:56

1:36

کوتاه

1:39

1:26

29:20

1:58

29:20

4:07

51:09

8:57

13:14

14:03

13:54

15:27

13:21

14:22

9:26

22:51

1:12

4:01

1:30:45

12:30

14:37

12:11

12:11

1:24

1:26

26:04

18:16

2:02

1:48

3:31

12:14

14:51

10:06