Gía trị của :\(\cos\left[\frac{\pi}{3}+\left(2k+1\right)\pi\right]\) bằng:( nêu cách làm)

A.\(-\frac{\sqrt{3}}{2}\) B. \(\frac{1}{2}\) C.\(-\frac{1}{2}\) D.\(\frac{\sqrt{3}}{2}\)

1/ Biểu thức: (nêu cách làm)

A = có kết quả thu gọn bằng: A.\(-\sin\alpha\) B.\(\sin\alpha\) C.\(-\cos\alpha\) D. \(\cos\alpha\) \(\cos\left(\alpha+26\pi\right)-2\sin\left(\alpha-7\pi\right)-\cot1,5\pi-\cos\left(\alpha+\frac{2003\pi}{2}\right)+\cos\left(\alpha-1,5\pi\right).\cot\left(\alpha-8\pi\right)\)

1/ Tìm m để bất phương trình :

a) (m - 1)x² - 2(m - 1)x-1 ≥ 0 nghiệm đúng với mọi x ϵ R.

b) (m - 4)x² - (5m - 20)x - 2m - 8 > 0 vô nghiệm.

Chứng minh các đẳng thức sau:

(với x là giá trị để biểu thức có nghĩa)

1/ \(\frac{\sin2x-\sin4x}{1-\cos2x+\cos4x}=-\tan2x\)

2/ \(\frac{\sin4x-\sin2x}{1-\cos2x+\cos4x}=\tan2x\)

I. Choose the correct answer A, B, C, or D to complete the sentence:

1) Having a college degree is a huge_____when it comes to getting a job.

A. advantage B. disadvantage C. efficiency D. inefficiency

2) The system has the_____to run more than one program at the same time.

A. knowledge B. recognition C. access D. ability

3) This is not really suitable reading_____for a young child.

A. material B. effect C. knowledge D. device

4) Swimming is a very____way of staying in shape.

A. portable B. enjoyable C. qualified D. high-status

5) Learning new vocabulary by translating slows____your learning process.

A. down B. by C. with D. from

6) I'm looking____some new applications to learn English more effectively.

A. for B. up C. in D. at

7) A____can be used to take notes with a digital pen on a touch screen.

A. smartphone B. laptop C. tablet D. computer

8) The ring____Linda is wearing is very expensive.

A. which B. that C. √ D. All are correct

II. Choose the underlined part that needs correction in each of the following questions:

1/ People use smartphones mostly for communicate.

A. communicate B. use C. for D. mostly

2/ My mum and dad, who they got married fifteen years ago, met over thirty years ago.

A. they B. married C. met D. over

3/ What is the name of the boy his father is the president of the School Parents Association?

A. What B. his C. of D. Parents

4/ Students are more excited to study when they work with differently types of apps.

A. with B. apps C. excited D. differently

1/ Tìm tham số m để phương trình ( m² - 2m + 3)x² - 2( m² -1)x + m -1 = 0 có hai nghiệm là hai số đối nhau.

2/ Tìm các giá trị của tham số m để bất phương trình sau có nghiệm đúng ∀x ϵ R

( m + 1)x² - 2( m + 1)x - m > 0

Chứng minh các đẳng thức sau:

1/ \(sin^6\alpha+cos^6\alpha=\frac{5}{8}+\frac{3}{8}cos4\alpha\)

2/\(\frac{1+sin2\alpha-cos2\alpha}{1+cos2\alpha}=tan\alpha+tan^2\alpha\)