Pin-код к банковской карточки содержит 4 цифры. Какова вероятность того, что pin-код состоит из четырех одинаковых цифр?

Найти угол, который образует с положительным лучом оси абсцисс касательная к графику функции y = (x^8/8) - (x^5/5) - (x√3) - 3 в точке x-нулевое = 1 Помогите пожалуйста! Срочно)

Маша хочет позвонить Кате, но не помнит последнюю цифру номера телефона Кати. С какой вероятностью Маша с первой попытки дозвонится Кате, если она знает, что последняя цифра нечётная?

Помогите пожалуйста!!!!
Употребить в правильной форме Present Perfect, Present Continuos, Present Simple, Past Simple
1.You (to remember) me ? We (to meet) here this month.
2. They already (to discuss) this question? - Yes, they ( to discuss) it last week.
3. Where mother (to put) my magazine? I (to look) for it now.
4. Whom you (to wait) for ? - We ( to wait) for the doctor.
The doctor ( to go) out some minutes ago.
5. I (not yo have) any news from them since they ( to leave )Kyiv.
6. Your children already (to read) this text? - Yes, they ( ot read) it at the last lesson.
7. There (to be) nobody here now. All the students ( to go) home.
8. It (to be) dark in the street now. the sun already ( to sit)
9. When you( to hear) the news? - I (to hear) them last Saturday.
10. What you (to do) now? - I (to write) a letter to my friend. - When you( to receive) his letter? - I (to receive )it today.
11. Your son already ( to do) his lessons ?- Yes, he just ( to finish) doing them and now he ( to watch) TV.
12. It (to rain )now? - No, it ( ot stop) rainig an hour ago and now the sun ( to shine )
13. She ( to learn) the new words and now she (to translate) the text.
14. Your child already (to get) a passport ?-Yes, he (to get) it two days ago.
15. It (to be )time to go. You ( to finish) your work?

Даны точки с координатами,точка A(a;5) и B(2;b). эти точки симметричны относительно прямой Y=3 найти "b"