Đây là bàn cờ vua

64 ô vuông là những ô có kích thước 1x1. Còn trên bàn cờ có 8 loại ô vuông từ 1x1 đến 8x8.
Ta nên đi ngược từ lớn tới nhỏ sẽ dễ hơn là đi ngược từ nhỏ tới lớn.
*Với ô vuông chứa 64 ô nhỏ==> cạnh là 8. Theo hàng dọc cũng như hàng ngang, chỉ có 1 cạnh dài 8 ô ( cạnh này kéo dài từ A->H và từ 1->8)
Vậy số ô vuông chứa 64 ô nhỏ là: 1x1 ô
*Tương tự với ô vuông chứa 49 ô nhỏ==> cạnh là 7. Theo hàng ngang ,có thể thấy 2 cạnh dài 7 ô (2 cạnh này Kéo dài từ A->G và từ B->H).Theo hàng dọc cũng có 2 cạnh dài 7 ô( 2cạnh này kéo dài từ 1->7 và từ 2->8)
Vậy số ô vuông chứa 49 ô nhỏ là: 2x2 ô
Tương tự với các số chính phương còn lại, sẽ có:
3x3 ô vuông có tính chất chứa 36 ô nhỏ
4x4 ô vuông có tính chất chứa 25 ô nhỏ
5x5 ô vuông có tính chất chứa 16 ô nhỏ
6x6 ô vuông có tính chất chứa 9 ô nhỏ
7x7 ô vuông có tính chất chứa 4 ô nhỏ
8x8 ô vuông có tính chất chứa 1 ô nhỏ

Tổng số ô vuông trên bàn cờ vua:
1x1 + 2x2 + 3x3 + 4x4 + 5x5 + 6x6 + 7x7 + 8x8 = 204 ô vuông

\(A=\dfrac{20}{1.6}+\dfrac{20}{6.11}+.........+\dfrac{20}{51.56}+\dfrac{20}{56.61}\)

\(\dfrac{1}{4}A=\dfrac{5}{1.6}+\dfrac{5}{6.11}+........+\dfrac{5}{51.56}+\dfrac{5}{56.61}\)

\(\dfrac{1}{4}A=1-\dfrac{1}{6}+\dfrac{1}{6}-\dfrac{1}{11}+........+\dfrac{1}{51}-\dfrac{1}{56}+\dfrac{1}{56}-\dfrac{1}{61}\)

\(\dfrac{1}{4}A=1-\dfrac{1}{61}\)

\(\Rightarrow A=\dfrac{60}{61}:\dfrac{1}{4}\)

\(\Rightarrow A=\dfrac{60}{61}.4\)

\(\Rightarrow A=\dfrac{240}{61}\)

De bai la j vay ban

III.Use the given suggestions to complete sentences.

1.He/know/few/English words/brother.

\(\Rightarrow\) He knows fewer English words than hiss breother.

2.There/many/big/city/coastal areas/our country.

\(\Rightarrow\) There are many big cities coastal areas in our country.

3.How/sugar/you need/make/cake?.

\(\Rightarrow\) How much sugar do you need to make a cake.

4.many plants/animals/danger/because/we/destroying/them.

\(\Rightarrow\) Many plants and animals are in dager because we are destroying them.

5.John/Nick/USA/and/speak/American English.

\(\Rightarrow\) John and Nick are from USA and they speak American English.

1. let is go to the movies.
what about going to the movies ?

2. i like watching tv better than playing video games.
i prefer watching TV to playing video games

3, mrs mai is a good english teacher.
mrs mai teacher English well

4. i spend two hours doing my washing every day.
it takes me hours to do my washing every day

VIII. Fill each gap of the folowing sentences with a suitable preposition.

1. Lan is standing at the bus stop. She is waiting ...........for.......... the train.

2. What time do you go home ..........from........... school?

3. Are there 5 fingers ..........in......... a hand?

4. My brother often takes the dog .........for.......... a walk in the evening.

5. Who do you go to school .......with........... ?

6. We always go .......to......... the city center .......by........ our own car.

7. I'd like to stay .......at.......... home tonight. Is there anything intesecting ............on......... T.V?

8. The Red River flows .......through........... the Gulf of Tonkin.

9. Jonh is often late ......for.......... school but I'm always early.

10. Let's listen .......to......... some music ........on......... the radio.

please put / in the other / the pictures / you here

=> Please put the picture in the order you here.

4x4+4x4+4-4x4=4x4+4x4+4-4x4+1

                      =4x(4+4+1-4)

                       =4x5

                       =20

Lim Festival
In 2017, I had chance to visit Lim Festival, a traditional festival in Vietnam where the famous Quan Ho folk songs are performed. This special festival was held on the thirteenth day of the first lunar month by local residents in Lim village, Bac Ninh province, Vietnam. Coming here on the festive days, I and thousands of visitors enjoyed the singing of traditional love duets (Quan Ho fork songs) performed by “lien anh” and “lien chi” (male and female Quan Ho singers) behind Lim pagoda, in Lim hill and on dragon boats on Lim rivers. Those singers wore traditional costumes and sang songs in pairs. There were strict rules for their performance in which the singers had to not only react quickly but also have a good understanding of traditional tunes as well as the historical and cultural features of the songs. Like other religious festivals, the Lim Festival went through all ritual stages, from the procession to the worshipping ceremony and other activities. I also watched a weaving competition among the village girls who wove and sang Quan Ho simultaneously. Other traditional games such as human chess-playing, cockfighting contest, rice-cooking contest, tug of war and wrestling were also held. Visiting this festival is a memorable experience to me.

VII. Complete the folowing sentences with the correct form of the verbs.

1. Look! She (come) .......is coming......... to our classroom.

2. He (not go) .....doesn't............ to the movies on Sunday nights.

3. I'd like (buy) ........to buy........ some oranges.

4. Your father (go) .......go........ to work by bike every day?

5. Tuan and his brother (not watch) .........aren't watching ........ T.V at the moment. They (be) ......are ....... asleep.

6. He usually (listen) ........listens........... to music and (watch) .......watchs .......... a newpaper in his free time.

7. I not (understand) ..........don't understand........... this sentences. What does this word (mean) .......mean......... ?

8. Their parents (travel) ........are going to travel.......... to Sa Pa next week.

9. (Not/ drive) ...............Don't drive............... your car too fast. It (be) ......is....... dangerous.