1. She found £10 beneath the sofa.
2. James filled to the police to report the incident.
3. He dived into the swimming pool twice.
4. He told me the truth.
5. I watched the last episode of my favourite TV series yesterday.
6. She sended him a present by post.
7. Mary crying a lot when she heard the bad news.
8. Brian went the train to London.
9. She felt happy when she got her jewels back.
10. Peter dropped my mother's antique vase. It broke into thousands of pieces.
11. Laura сalled her mother as soon as she arrived in Paris.
12. He stoped talking when I walked into the room.
13. She tryed to stop the thief, but he got away.
14. She took the glass with orange juice.
15. Miss Marple solved many mysteries in St Mary Mead.
GOOD LUCK
Пошаговое объяснение:
а) 4,8,12,16…;
=4n
б) 1,-1,1,-1….
=
2. Последовательность задана в аналитической форме yn=2n+10
Найти 10,50,63 член последовательности.
y₁₀=2·10+10=30
y₅₀=2·50+10=110
y₆₃=2·63+10=136
3. Последовательность задана в аналитической форме yn=n² +2.
Найти 5,10,13 член последовательности.
y₅=5²+2=25+2=27
y₁₀=10²+2=102
y₁₃=13²+2=171
4. Последовательность задана в рекурсивном виде y1=5
y n =y n-1 −3 , если n=2,3,4…
Найти 5,11,12 член последовательности.
y₅=y₄-3=y₃-3-3=y₂-3-3-3=y₁-3-3-3-3=y₁-4·3=5-4·3=-7
y₁₁=y₁₀-3=...=y₁-(11-1)·3=5-10·3=-25
y₁₂=y₁₁-3=...=y₁-(12-1)·3=5-11·3=-28
Это арифметическая прогрессия с разностью -3. Несложно доказать преобразуя данное рекурсивное соотношение
5. Последовательность задана в рекурсивном виде y 1 =3, y 2 =8 , y n =2y n-2 +3,
если n=3,4,5…. Найти 3,4,9 член последовательности.
y₃=2y₁+3=2·3+3=9
y₄=2y₂+3=2·8+3=19
y₅=2y₃+3=2·9+3=21
y₆=2y₄+3=2·19+3=41
y₇=2y₅+3=2·21+3=45
y₈=2y₆+3=2·41+3=85
y₉=2y₇+3=2·45+3=93
18:3равно6
3*3равно9