VP `=(a+b)(a^2-ab+b^2)`

`=a^3-a^2b+ab^2+a^2b-ab^2+b^3`

`=a^3+(a^2b-a^2b)+(ab^2-ab^2)+b^3`

`=a^3+b^3`

.

VP `=(a-b)(a^2+ab+b^2)`

`=a^3+a^2b+ab^2-a^2b-ab^2-b^3`

`=a^3+(a^2b-a^2b)+(ab^2-ab^2)-b^3`

`=a^3-b^3`

1. so
2. such
3. such
4. such
5. so
6. such
7. so
8. such (a great success ?)
9. enough
10. too
.
3. The patient was so weak that he couldn't get up.
4. This room is so dark that I can't study.
5. This room isn't big enough for us to take the meeting.
6. The test was not easy for us to do it.
7. The map is too old for me to read.
8. He didn't speak slowly enough for us to hear him well.
.
1. That woman was so tall that she could....
2. This could is too big for me to wear.
3. The coffee was so strong that she couldn't....
4. That bag was so heavy that none of....
5. The stadium is big enough to hold 60 000 people.
6. The question was too hard for us to answer.
7. The TV program is so exciting that the children....
8. You are not old enough to drive that car.

`(5-7x) vdots (x-2)`

`<=> -7(x-2)+9 vdots (x-2)`

`<=> 9 vdots (x-2)`

`<=> (x-2) \in {-9;9;-3;3;-1;1}`

`<=> x \in {-7;11;-1;5;1;3}`.

`tan3x=tanx`

`<=>3x=x+kπ`

`<=>x=k π/2`

Phương trình có `4` điểm biểu diễn các nghiệm: `π/2 ; π ; (3π)/2 ; 2π`.

ĐK: `x>=3`

`\sqrt(x^2-9)-3\sqrt(x-3)=0`

`<=>\sqrt((x-3)(x+3))-3\sqrt(x-3)=0`

`<=>\sqrt(x-3)(\sqrt(x+3)-3)=0`

`<=> [(\sqrt(x-3)=0),(\sqrt(x+3)=3):}`

`<=> [(x-3=0),(x+3=9):}`

`<=> [(x=3),(x=6):}`

Vậy `S={3;6}`.

4 không thấy có vấn đề ?

5. Jack isn't as old as he looks.

6. They haven't lived here as long as we've lived.

1. Living in the city is noisier than living in the country.
2. My suitcase is not as small as my backpack.
3. It is more expensive to travel nowadays.
4. In the past it was not easy to find a job as now.
5. Jack isn't as young as he looks.
6. They haven't lived here as long as they've lived.
7. The station wasn't as far as I thought.
8. Our visit to the museum was more boring than we expected.
9. My ruler is not different from his.
10. Your hair is as long as mine.

The heavy snow prevented them from finishing the match.

1. Henry sometimes goes to bed early.

2. John was doing homework at 9 pm yesterday.

3. They didn't go to school last Monday.

4. Mary can swim but she can't play tennis.

5. Tuan has got many books on the shelf.