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
Надо решить такое уравнение:
2x^3 + 9x^2-4=0
Для вычисления корней этого кубического уравнения используем тригонометрическую формулу Виета, которая работает для уравнений вида:
x^3 + ax^2 + bx + c = 0. Если уравнение не такого вида, то его можно получить поделив всё уравнение на коэффициент возле x^3.
В нашем случае a = 4.5, b = 0 и c = −2.
1. Вычисляем
Q=(a2- 3b)/9 2,25
R=(2a3 - 9ab + 27c)/54 2,375
2. Вычисляем
S = Q^3 - R^2 5,75
3. a) Если S>0, то вычисляем
φ=(arccos(R/Q3/2))/3 0,703703704
И наше уравнение имеет 3 корня (вещественных):
x1= - 2(Q)1/2cos(φ) - a/3 = -4,396531134.
x2= - 2(Q)1/2cos(φ+2π/3) - a/3 = 0,624712566.
x3= - 2(Q)1/2cos(φ-2π/3) - a/3 = -0,728181432.