Из двух городов, расстояние между которыми 960 км, шли два поезда навстречу друг другу и встретились на середине пути. Первый поезд шёл со средней скоростью 60 км/ч, а второй - 80 км/ч. Какой поезд затратил на путь до встречи больше времени и на сколько часов?

Докажите,что значение выражения 5х^3-5(х+2)(х^2-2x+4) не зависит от значения переменной.

РЕБЯТ,РЕШИТЕ СРОЧНО 

I. Закончите следующие предложения, употребив данные в скобках глаголы и словосочетания в нужной форме: 1. The secretary wondered if... (to arrive by plane). 2. She told us that... (to reserve a room). 3. The receptionist asked me whether... (to reserve a table). 4. He answered that... (to have no accommodation). 5. The porter told me that... (to attend to my suit-case). 6. I didn't know when ... (to serve dinner). 7. I wonder if... (to have the key). 8. The chambermaid let me know that ... (to bring an extra blanket). 9. Mr. Teplov told the chambermaid that... (to have bis suit pressed). 10. I'm wondering how ... (to fill in a form). 11. I'd like to know whether... (to be available). 12. We didn't know that... (to wait for the plane). 13. The chambermaid answered me that... (to bring my suit).

II. Раскройте скобки, употребив глагол в нужной форме: Mr. Zotov of the Russian Trade Delegation (to receive) a fax from Moscow. It said that Mr. Losev of Machinoimport (to arrive) in London on business the next day. Mr. Zotov told the secretary that she (must, to reserve) a room for Mr. Losev at the Imperial Hotel for 5 nights. Before Mr. Losev (to arrive) in London, the secretary (to reserve) a room his name at the Imperial Hotel. She also (to phone) the airport and (to find out) when the jet-liner from Moscow (to arrive). At 4 p.m. Mr. Zotov (to wait) for Mr. Losev at the airport. Soon he (to hear) the announcement that the plane (to land). He (to see) Mr. Losev when the passengers (to get off) the plane. Mr. Zotov (to be) glad to see Mr. Losev in London. After Mr. Losev (to go) through the Customs, they (to go) to the hotel.

III. Заполните пропуски артиклями, где необходимо: ... other day Mr. Goodwill, ... representative of Brighton & Co., arrived in Moscow on business. Mr. Mitin, director of our office, met him at Sheremetievo Airport and brought him to ... Metropol Hotel. Mr. Mitin had reserved accommodation for Mr. Goodwill there two days before. ... hotel-porter met them at... door and showed them to reception-desk. Some people were waiting at... desk. ... receptionist gave Mr. Goodwill... form and asked him to write his name, ... address,... nationality and ... ocupation. As Mr. Goodwill knew Russian well it didn't take him long to fill in ... form. After he had done all ... formalities, ... receptionist gave Mr. Goodwill... key to his room and ... porter showed him into it. It was... nice single room on ... second floor. Mr. Goodwill liked ... room very much and he thanked Mr. Mitin. They made ... appointment for the next morning and Mr. Mitin left... hotel.

IV. Заполните пропуски предлогами и наречиями, где необходимо: 1. I wonder what hotel they are staying .... 2. Mr. A. asked the secretary if she had reserved accommodation ... him ... the Grand Hotel. 3. Would you like to have a single room ... a private bath? 4. He said that they would arrive ... London ... Sunday. 5. Will you help me to fill... the form. It is... French and I don't know this language. 6. We didn't have the key... our office and couldn't get.... 7. When we arrived ... the office Mr. S. had already left. 8. Will you attend ... this inquiry, please. We received it last week and haven't yet sent them our catalogues and price-lists. 9. I looked ... my watch. It was half... ten.

При нагріванні технічного купрум (ІІ) нітрату масою 75,2 г утворився кисень об'ємом 4 л (н.у.). Обчислити масову частку домішок в даному зразку нітрату.Допоможіть, заранє дякую!

упростите выражение используя формулы сокращенного умножения (2p-3)(2p+3)+(p-2)^2