\(y=\sqrt{3}cos2x+2sinxcosx-2\)

\(=\sqrt{3}cos2x+sin2x-2\)

Ta có: \(\left|\sqrt{3}cos2x+sin2x\right|\le\sqrt{\left(\sqrt{3}\right)^2+1^2}=2\)

Do đó \(-2\le\sqrt{3}cos2x+sin2x\le2\)

\(\Leftrightarrow-4\le\sqrt{3}cos2x+sin2x-2\le2\).

Ta có: \(\left|\sqrt{3}cosx-sinx\right|\le\sqrt{\left(\sqrt{3}\right)^2+\left(-1\right)^2}=2\)

Do đó \(-2\le\sqrt{3}cosx-sinx\le2\)

Dear Liu!

Last time I told you that I had been thinking about pursuing higher education in the UK. I got started to learn the process of applying for a university in London some time ago. Now I have some questions for you. 

First, what is the procedure for applying for a student visa? Of course. I have to submit an application but what other documents are required? How long does it take me to obtain my student visa? It is important to plan time to wait for visa processing because the time between finding out I have been accepted to go and leaving may be very close together. Second, do 1 have to present my financial documents; for example proof of funds, to prove that I am able to pay for my education? And last, do I need to obtain the International Certificate of Vaccination? Is it required that I have certain vaccinations before I go? What are they? After all. can you make me a checklist: what I should bring and what I should leave at home? 

I wish you and your family the best. I look forward to hearing from you soon. 

                                                                                                     Regards, 

                                                                                                     Mai Anh

Mong cô duyệt bài ạ:

Dear Duc Son,

Last time I told you that I had been thinking about pursuing higher education in the UK. I got started to learn the process of applying for a university in London some time ago. Now I have some questions for you.

First, what is the procedure for applying for a student visa? Of course. I have to submit an application but what other documents are required? How long does it take me to obtain my student visa? It is important to plan time to wait for visa processing because the time between finding out I have been accepted to go and leaving may be very close together. Second, do 1 have to present my financial documents; for example proof of funds, to prove that I am able to pay for my education? And last, do I need to obtain the International Certificate of Vaccination? Is it required that I have certain vaccinations before I go? What are they? After all. can you make me a checklist: what I should bring and what I should leave at home?

I wish you and your family the best. I look forward to hearing from you soon.

Regards,

Dang Phong

a) Vì số bi trong hộp thứ nhất và hộp thứ hai là độc lập và việc lấy ra số các bi từ hai hộp là độc lập nên hai biến cố A, B là độc lập. 

b) 

- Trên A:

+ Hai quả lấy ra đều màu đỏ: \(P=\frac{C^2_3}{C^2_5}=\frac{3}{10}\).

+ Hai quả lấy ra cùng màu: \(P=\frac{C^2_3+C^2_2}{C^2_5}=\frac{4}{10}\)

+ Hai quả lấy ra khác màu: \(P=1-\frac{4}{10}=\frac{6}{10}\).

- Trên B: 

+ Hai quả lấy ra đều màu đỏ: \(P=\frac{C^2_4}{C^2_{10}}=\frac{2}{15}\).

+ Hai quả lấy ra cùng màu: \(P=\frac{C^2_4+C^2_6}{C^2_{10}}=\frac{7}{15}\)

+ Hai quả lấy ra khác màu: \(P=1-\frac{7}{15}=\frac{8}{15}\).

Giải phương trình cos3xcos3x−sin3xsin2x=2−3√28 

phong chữ nào z ?

Bn tk đăng câu hỏi linh tinh à

trả lời:

xl bạn mk ở tỉnh hòa bình nha!

hok tốt

quê mình phú thọ chứ mình sống ở hà nội

Phương trình đã cho <=> (2sinx + 1).(3cos4x +2sinx -4) = 3 - 4(1- sin^2 x) 
<=> (2sinx + 1)(3cos4x + 2sinx - 4) = 4sin^2 x - 1 
<=> (2sinx + 1).(3cos4x + 2sinx - 4) = (2sinx + 1).(2sinx - 1) 
<=> (2sinx + 1).(3cos4x + 2sinx - 4) - (2sinx + 1).(2sinx - 1) =0
<=> (2sinx + 1)(3cos4x + 2sinx - 4 - 2sinx+ 1) = 0
<=> (2sinx + 1)(3cos4x -3) = 0
<=>  (2sinx + 1)(cos4x - 1) = 0
(Đến đây pt tích dễ rồi tự giải nha)

poor -> impoverished