Предмет: Алгебра, автор: michnodima

Решить уравнение 2sin^2x+5cosx = 4

Ответы

Автор ответа: Vamdemon

Произведем замену, косинус икс равно t: 2(1-t^2)+5t-4=0; 2t^2-5t+2=0; D=9 t=-1; cosx=-1; x=П+2Пn

Предыдущий вопрос

Следующий вопрос

Похожие вопросы

Предмет: Математика, автор: oleksandrio2002

ПОМОГИТЕ ПОЖАЛУЙСТА. СРОЧНО НАДО.
-12,5×4×(-8)×(-5)

7 лет назад

Предмет: Английский язык, автор: melikuzievbehruzt

помогите с тестами 1. Do you like_____ football on TV?
A) watch
B) watched
C) watches
D) watching
2. Thank you for_____ me.
A) helping
B) help
C) to help
D) helped
3. I’m afraid of _____ mistakes.
A) to make
B) made
C) make
D) making
4. It is important _____.
A) to win
B) winning
C) win
D) won
5. My mother does all the _____.
A) cleaning
B) to clean
C) cleans
D) clean
6. I _____ a friend while I _____ the shopping.
A) was meeting / did
B) met / was doing
C) meet / do
D) met / did
7. I _____ for my things when I ____ someone call my name.
A) paid / was hearing
B) pay / heard
C) was paying / hear
D) was paying / heard
8. I _____ and I _____ the knife.
A) cooked / was dropping
B) cook / drop
C) was cooking / dropped
D) cooked / dropped
9. I stopped _____ my book and went to bed.
A) to read
B) read
C) will read
D) reading
10. My teachers always expected me _____ well in exams.
A) did
B) doing
C) do
D) to do
11. Let me _____ for the meal. You paid last time.
A) pay
B) to pay
C) paid
D) paying
12. The dentist told me _____ more careful when I brush my teeth.
A) will be
B) being
C) to be
D) be
13. The sports competitions which ___ on Sunday ___ by a lot of people.
A) are held / will be visited
B) was held / will visit
C) will held / will visit
D) have been held / have visited
E) will be held / will be visited
14. The business letter ___ just ___ .
A) is / written
B) has / been written
C) was / written
D) were / written
E) is / going to write
15. All the business letters ___ yesterday. They ___ to the post office immediately.
A) answered / take
B) were answered / took
C) are answered / were taken
D) answered / took
E) were answered / were taken
16. I ___ that I ___ at the station at 5.
A) was told / should be met
B) told / is being met
C) tells / am met
D) am told / was met
E) will be told / would be met
17. By the time we came to the bookshop all books ___
A) are sold
B) were sold
C) had been sold
D) are being sold
E) is being sold
18. I have ___ time than he does.
A) bigger
B) larger
C) most
D) less
E) least
19. Your English is much ___ now. You’ve made___ mistakes this time.
A) best / least
B) better / less
C) the best / less
D) good / less
E) best / the least
20. Please, tell me something ___ than this old joke.
A) interesting
B) less interesting
C) more interesting
D) the most interesting
E) the least interesting
21. It is much ___ to speak English than to understand.
A) -
B) the most difficult
C) more difficult
D) difficult
E) most difficult
22. Выберите правильные формы для глагола "начинать".

Infinitive
Past Simple
Past Participle

a)
begin
began
began

b)
begin
began
begun

c)
begin
begun
began

d)
began
begin
begun

23. Укажите правильную форму Past Participle глагола "рисовать".
a) drew
b) draw
c) drewn
d) drawn
24. I have broken my pen. I see you have finished writing your exercise. Please give me ...
a) mine
b) its
c) yours
d) ours
25. Our twins were born on the same day as their twins. But ... look bigger than ...
a) ours, theirs
b) theirs, its
c) ours, hers
d) theirs, his

7 лет назад

Предмет: Алгебра, автор: jaremchukdarina

у геометричній прогресії (bn) B4=48 q=-4 знайти в1?

7 лет назад

Предмет: Математика, автор: poltavetska

вырази в см,это дроби .Я не знаю как пишется дробь ,поэтому напишу через запятую.Короче вот 3,4 Метра,1,2 метра,3,5 метра,4,5 метра.Это 112 номер. Потом ,вырази в метрах.3,4 км,4,5 км,3,4 км,1,8км,7,8 км .Это 114 номер. Потом вырази в центнерах.1,2 т,1,5 т,3,5 т,4.5т,1,10т. Это 118 номер. И номер 120 ,вообще не знаю как писать.

10 лет назад

Предмет: История, автор: Jedup

Назовите факты свидетельствующие о бурном развитии российской экономики в конце 19- начале 20 веков. также назовите, что тормозило этот процесс. Помогите, пожалуйста)

10 лет назад