Đề sai rồi nhé b

28.69+4.18.7+2.14.13

=4.7.69 +4.7.18 +2.2.7.13

=4.7.69 +4.7.18 +4.7.13

=4.7(69+18+13)

=28.(62+18+13+7)=28(80+20)=28.100=2800

286 chia cho a dư 48, có nghĩa là a khác 2 (vì 286 là số chẵn nếu chia 2 thì sẽ hết, ở đây thì có dư) , và a>48 ( sô dư luôn bé hơn số chia) . Suy ra 286-48=238 chia hết cho a, 969-17=952 chia hết cho a

DO đó a là ước chung của 238 và 952. Mà ước chung của (238;952)={2;7;17,14,34,119}. Ta đã nói a khác 2, a>48 nên chỉ có 119 là số tư nhiên a cần tìm.

1.uses

2.cuts

3.makes

4.decides

5.watched

6. thought

Ex11: Chia các động từ trong ngoặc ở thì hiện tại đơn hoặc quá khứ đơn :

Mr.Tam is a teacher. Two years ago, he taught math in a small school in the country. But now he teaches at a high school in the city.

Every day, Mr Tam gets. up at half past five. After his morning exercises, he takes bath and has breakfast with his wife. Then he leaves home for school at a quarter to seven.

Yesterday was Sunday. Mr.Tam didn't go to school. He and his wife visited his parents in the countryside. He bought them lots of presents. Mr.Tam and his wife spent their day off them lots of presents. They returned home at 9:30 in the evening.

1. Geography

2.Chemistry

3.Physics

4. Science

5. Biology

6. Literature

7. Dictionary

8. Novel

What time - too - class - timetable - an - favorite - will - Physics

An : I don't have my timetable. What do we have today , Minh?

Duy : We have math , physics, History and English

An : What time do we have Physics ?

Duy : We have it from 7.45 to 8.30

An : What class will we have tomorrow ?

Duy : We will have Geography , Art , Music and Physical Education

An : What is your favorite subject , Duy ?

Duy : I like Math most. It's interesting and important subject.

An : Yes , I like Math too

1. It is thought that the prisoner escaped by climbing over the wall.

-> The prisoner is thought to escape by climbing over the wall

-> People thought that the prisoner escaped by climbing over the wall.

2. It is reported that the building was badly damaged by fire.

-> The building is reported to have been damaged by fire

-> They report that the building was badly damaged by fire.

3. People say that he is a good doctor.

-> He is said to be a good doctor

-> It is said that he is a good doctor

\(n^2\left(n+1\right)+2n\left(n+1\right)\\ =\left(n^2+2n\right)\left(n+1\right)\\ =n\left(n+2\right)\left(n+1\right)\)

Vì n, (n+1) và (n+2) là ba số tư nhiên liên tiếp do đó tích của 3 số này sẽ chia hết cho 2 và 3 --> chia hết cho 6