\(0\le a\le b\le c\le1\\ \Rightarrow\left(a-1\right)\left(b-1\right)\ge0\\ \Rightarrow ab-a-b+1\ge0\\ \Rightarrow ab+1\ge a+b\\ \)

Chứng minh tương tự ta được :

\(bc+1\ge b+c\\ ac+1\ge a+c\)

\(\Rightarrow\dfrac{a}{bc+1}+\dfrac{b}{ac+1}+\dfrac{c}{ab+1}\\ \ge\dfrac{a}{b+c}+\dfrac{b}{a+c}+\dfrac{c}{a+b}\\ \ge\dfrac{a+a}{a+b+c}+\dfrac{b+b}{a+b+c}+\dfrac{c+c}{a+b+c}\\ =\dfrac{2\left(a+b+c\right)}{a+b+c}=2\)

:v .

chu vi lẫn diện tích bằng nhau mà

chuyển thành câu bị động

Do they put garbage bins along the streets in your town ?

-> Are garbage bins along the streets put in your town

Bài 1:Điền although,despite , in spite of, however, hoặc nevertheless vào chỗ trống thích hợp

1.They are still playing football.......................although......it is raing hard

2,.......Although.........I heard the telephone ring, I didn't answer it

3.We enjoyed our holiday..............in spite of.............the bad weather

4........Although..........he got top marks at high school, he never went to university

5........Atlthough........there was no electricity, I was able to read because I had a candle

6.She failed the test............although.....she studied hard

7...........In spite of .........difficulties, the firemen managed to save many people who were caught in the fire

8.Everyone thought she would accept the offer. .........Nevertheless.......,she turned it down

9.Carol arrived at the meeting.........although.....I asked her not to be there

10.They performed successfully.....in spite of ..............not preparing carefully

11...........Although..........it was raining heavily, he went out without a raincoat

12.Some English words have the same pronunciation...............although.....they are spell differently, for example, dear and deer

Phùng Gia Bảo cũng là bình phương của 1 số âm lun nên gọi số chính phương là = bình phương của 1 số nguyên

là số = bình phương của 1 số nguyên

1. I wish I (have/ has/ had) a lot of interesting book.

2. I wish I (would meet/ met/ meet ) her tomorrow.

3. I wish I (was/ were/ am) your sister.

4. I wish they ( won/ had won/ would win) the match last Sunday

5. I wish they ( played/ playing/ play) soccer well.

6. She wishes she (will/ would/ can) come here to visit us.

7. I wish yesterday ( were /was/had been ) a better day.

8. I wish I (can speak/ could speak/ will speak) many languages

9. I wish tomorrow ( were/ will be/ would be) Sunday.

10. I wish I ( am/ was/ were) a movie star

1. Although he promised that he wouldn't be late , he didn't arrive until 9 o'clock
=> He didn't arrive until 9 o'clock ; despite the fact that he promised that he wouldn't be late.
2. She wasn't nearing the coat although it was quite cold
=> She wasn't nearing the coat in spite of the cold
3 . We though we had better invite them to the party although we don't like them

=> we though we had better invite them to the party in spite of not liking them .