Cứ 1 điểm nối với 4 điểm còn lại thì được 4 đoạn thẳng

Vậy 5 điểm thì nối được: 5.4= 20 đoạn

Do đó 100 điểm thì nối được 100 . 99 = 9900 đoạn

Có n điểm thì nối được: n( n -1) đoạn

My hobby is (1)collecting books. I collect books whenever I have money and need some books. I collect many kinds of books such as (2) books about animals and plants;story books or (3)books about school subjects. I am learning at school, you know English, Maths, History, Geography. Biology ; and books about (4)speaking countries.

I buy books from (5) a bookshops near my house and some others from (5) second-hand book stalls. I also get books from (6) friends or family members.

I collect books because I would like to (7) get information and facts from books. They help me boarden (8) knowledge and understanding

In the future, I try to make my collection (9) larger I would like to open (10) the library of my own.

1. My father doesn't play football anymore 2.1 was given a present on my last birthday
3. She suggests going swimming
4. He invited me a cup of tea
5. If we had had a map, I wouldn't got lost in the jungle

6.1 haven't seen Bob since I was in Ho Chi Minh City

7. It takes three hours to drive from Hanoi to Namdinh. 8.1 wish you had told us about it
9. The owner of the house is thought to be abroad
10. The sea was too rough for the children to go swimming

Bạn phải nên hiểu là như thế này, việc tổ chức cuộc thi và lên danh sách không hề nhanh, gọn và dễ dàng. Bản thân người tổ chức cũng đã lên kế hoạc từ trước (thậm chí rất lâu). Việc lỡ thời gian là việc không ai mong muốn. Tuy nhiên, đó là do bạn chứ không phải ai khác nên đừng nói những từ như ''bất công''. Nghe mất lòng (đụng chạm nhua nữa) bạn nhé!

Hi! Everybody. What kinds of foods do you like? My favourite food is Pho. Pho is the most popular food among the population and it plays an importance thing in the spirit of Vietnamese people, especially the people who live in Ha Noi. Anyone feels hungry in a short time in the morning can also
enjoy a bowl of hot and spicy Pho to fill their empty stomach. Have many Pho but there are two main kind of Pho: Pho with beef and Pho with chicken. The ingredients of Pho are rice noodles and borth which is generally made by simmering bones, flanlsteak charred onion and spices, it takes several hours to prepare. When people eat Pho they can add some kind of thing such as chilli, peper,"dam"...I love Pho very much I can eat it everyday without boring. I'm sure that you do it, too. Wherever in Vietnam Pho is special food.

\(3D=3^{11}-3^{10}+3^9-...+3^3-3^2\)

3D  + D = \(3^{11}-3^{10}+3^9-...+3^3-3^2+3^{10}-3^9+3^8-3^7+..+3^2-3^1\)

4D         \(=3^{11}-3\)

=> D = \(\frac{3^{11}-3}{4}\)

Tick đúng nha 

B=70

C=110

D=110

I love my family because I love all members of my family. In my opinion, a happy family is that the couple can have intimate communication and they have no connection with social status.

I love my family because I love all members of my family. And I think, a happy family is that the couple can have intimate communication and they have no connection with social status.

mk hat cach mk cung chi hieu the nay thoi