Rút gọn biểu thức: B = 2 sin 2 a -   sin 2 a . cos 2 a 2 sin 2 a + 2 sin 2 a . cos 2 a :

A.  tan 2 a

B. tana

C.  tan 2 2 a

D. tan2a

Cho đồ thị hàm số hàm y = x 3 - 3 x + 1  là hình bên. Dựa vào đồ thị hàm số đã cho hãy tìm m để phương trình  y = x 3 - 3 x - m có 3 nghiệm phân biệt

A.  - 1 < m < 3

B.  - 2 < m < 2

C.  - 2 ≤ m ≤ 2

D.  - 2 ≤ m ≤ 3

Put the verbs in parentheses into the correct form.

If someone (walk).............................. in here with a gun, I would be very frightened.

Read the passage and choose one correct answer for each question.

PREPARING A DINNER PARTY

       Giving a dinner party is a wonderful way of entertain people. You can also make new friends and give others the chance to get to know each other better.

       It needs planning, though. First, make a guest list, with different kinds of people and a mixture of women and men. Don’t invite couples because they aren’t so much fun.

       When you know who can come, find out what they like to eat and drink. Note down any who are vegetarians, or who can’t eat or drink certain things for religious seasons.

       Then plan their menu. Include a first course, a choice of main courses and a dessert, plus lots of people’s favourite drinks.

       The next thing to do is the shopping. Make sure buy more than enough of everything, and that someone can help you carry it!

       On the day, start cooking early. Give people appetizers like Greek mezze or Spanish tapas, so they don’t get hungry if they have to wait. Serve the delicious meal, sit down with your guests and have a good time – you’ve earned it!

When giving a dinner party, you should NOT invite ........................ .

A. husbands and wives.

B. those who are vegetarians.

C. both women and men.

D. those who can’t eat or drink certain things.

 Cho a là số thực dương, khác 1. Khi đó a 2 3 4  bằng:

A.  a 8 3

B.  a 6  

C.  a 2 3

D.  a 3 8