ta có 1/2^2<1/1.2;1/3^2<1/2.3;...;1/2002^2<2001.2002;1/2003^2<1/2002.2003

suy ra 1/1.2+1/2.3+...+1/2001.2002+1/2002.2003

= 1-2/2+1/2-1/3+...+1/2001-1/2002+1/2002-1/2003

=1-1/2003

mà 1/2^2+1/3^2+...+1/2002^2+1/2003^2<1-1/2003<1

Ta có:

1/2² = 1/1.2

1/3² < 1/2.3

1/2002² < 1/2001.2002

1/2003² < 1/2002.2003

Suy ra : 1/2² + 1/3² + 1/2002² + 1/2003² < 1/1.2 + 1/2.3 + 1/2001.2002 + 1/2002.2003

1/2² + 1/3² + 1/2002² + 1/2003² < (1 - 1/2 + 1/2 -1/3 )+(1/2001 - 1/2002 + 1/2002 -1/2003)

1/2² + 1/3² + 1/2002² + 1/2003² <  2/3 +1/2002 -1/2003<1

1/2² + 1/3² + 1/2002² + 1/2003² < 1

"đi khắp bầu trời : mẹ là tốt nhất ; ăn khắp trăm món : muối vẫn hàng đầu "

kb nhé

My name is Long and I’m a Vietnamese. I am twenty-four years old. I live in Ho Chi Minh city in the south of Vietnam.

I have a big family with six people. I have two sisters and a brother. My sisters are older and my brother is younger than me. My father is a teacher at a secondary school. He has worked for 35 years in the field and he is my biggest role model in life. My mother is a housewife. She is nice and she is really good at cooking. I love my family so much.
I’m a generous and easy-going person but when it comes to work I’m a competitive perfectionist. I’m also an optimis and outgoing person so I have many friends and other social relationships. I enjoy reading, writing and doing math. I decided to become a Civil Engineer because I have always been fascinated by bridges, buildings, and skyscrapers. A degree in Civil Engineering enables me to achieve my goals and also gives me an opportunity to make a difference in the community.

Five years from now, I want to become a project manager of a construction project. As a project manager, my primary goals are managing people, set budgets, and making decisions of all kinds. I also want to speak English fluently so I can work with people from different countries.

my name is kien 

i am 12 year old

hết

đề có thiếu ko cậu

Put the words in the correct oder :

1 . from / vacation / come / Nha Trang / I / just / have / a / back / in .

->........... I just have come back from a vacation in Nha Trang.........................

2 . university / Viet Nam / the / was / Quoc Tu Giam / first / in

->...........The Quoc Tu Giam was the first university in VietNam.........

3 . world / sĩ / in / are / continents / there / the .

->...........There are six continents in the world...................

4 . England / tower / it / famous / in / the / is / most .

-> ............It is the famous tower in England...........................

5 . years / new / building / is / but / looks / 100 / more than / old / the it .

=> The old building is more than 100 years but it looks new

1 . from / vacation / come / Nha Trang / I / just / have / a / back / in .

=>I just have come back from a vacation in Nha Trang.

2 . university / Viet Nam / the / was / Quoc Tu Giam / first / in

->The Quoc Tu Giam was the first university in VietNam.

3 . world / sĩ / in / are / continents / there / the .

=>There are six continents in the world.

4 . England / tower / it / famous / in / the / is / most .

=>There are six continents in the world.

5 . years / new / building / is / but / looks / 100 / more than / old / the it .

=>The old building is more than 100 years but it looks new.

BẠN VẪN ON À????????

MUỘN VẬY

3/2 bạn nhé

1. E
2. H
3. A
4. G
5. B
6. C
7. D
8. F