\(\frac{1}{5\cdot8}+\frac{1}{8\cdot11}+...+\frac{1}{x\left(x+3\right)}=\frac{101}{1540}\) (dấu . là nhân nhé)

 => \(\left(\frac{1}{5}-\frac{1}{8}+\frac{1}{8}-\frac{1}{11}+...+\frac{1}{x}-\frac{1}{x+3}\right):3=\frac{101}{1540}\)

=> \(\left(\frac{1}{5}-\frac{1}{x+3}\right):3=\frac{101}{1540}\)

=> \(\frac{1}{5}-\frac{1}{x+3}=\frac{101}{1540}\cdot3=\frac{303}{1540}\)

=> \(\frac{1}{x+3}=\frac{1}{5}-\frac{303}{1540}=\frac{1}{308}\)

=> \(x+3=308\Rightarrow x=308-3=305\)

minh/friends/be/going to/have/picnic/near/lake

=> Minh and his friend are going to have a picnic near a lake.

which/be/biggest/city/viet nam

=> Which is the biggest city in Viet Nam?

Complete the sentences with the comparative form of the adjectives in brackets

1. Which river is longer, the Red Rive or the Mekong Rive? (long)

2. Which animals are more intelligent, dogs or dolphins? (intelligent)

3. Which language is difficult,Chinese or English?(difficult)

4. Which mountain is higher, Mount Everest or Mount Fuji?(high)

Write sentences using the words or phrasses or phrases given:

1. My father/ old/ Uncle Hung

=> My father is than Uncle Hung.

2. winter/ cold/ spring

=> Winter is colder than spring.

3.Ha noi Opera House/ big/ Hai Phong Opera Huose

=> Ha Noi Opera House is bigger than Hai Phong Opera House.

4.A house in the city centre/ expensive/ a huose in the suburb

=> A house in the city centre is more expensive than a house in the suburb.

5.hue/historic/ Hoi An

=> Hue is more historic than Hoi An.

6.Travelling by train/ comfortable/travelling by coach

=> Travelling by train is more comfortable than travelling by coach.

7. living in the country/ peaceful/ living in the city

=> Living in the country is more peaceful than living in the city.

Hãy tìm từ thích hợp để điền vào chỗ trống: 7800kg /m3 là........ của sắt.