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27 tháng 3 2017

ta có \(\left(n^2-n+1\right)+\left(n^2+n+1\right)\\ =n^2-n+1+n^2+n+1\\ =2n^2+2\)

=>\(n\in\left\{n\in N\right\}112\le n\ge123\)

28 tháng 3 2017

bài này mk k bt cách trình bày nhưng kết quả hình như là 15 đó bạn....

9 tháng 3 2017

câu 10: 55

9 tháng 3 2017

câu 9 là 2

I. Read the following passage and decide if it is T or F.Many people still believe that natural resources will never be used up. Actually, the world’s energy resources are limited. Nobody knows exactly how much fuel is left. However, we also should use them economically and try to find out alternative sources of power. According to Professor Marvin Burnharm of the New England Institude of Technology, we have to start conserving coal, oil and gas before it is too late; and nuclear power is the...
Đọc tiếp

I. Read the following passage and decide if it is T or F.

Many people still believe that natural resources will never be used up. Actually, the world’s energy resources are limited. Nobody knows exactly how much fuel is left. However, we also should use them economically and try to find out alternative sources of power. According to Professor Marvin Burnharm of the New England Institude of Technology, we have to start conserving coal, oil and gas before it is too late; and nuclear power is the only alternative.

However, many people do not approve of using nuclear power because it’s very dangerous. What would happen if there was a serious nuclear accident? Radioactivity causes cancer and may badly affect the future generations.

The most effective thing is that we should use natural resources as economical as possible.

Statements

T/ F

1. Natural resources will run out.

2. The world’s energy resources are unlimited.

3. We know exactly how much fuel is left.

4. We should use fuel economically.

5. According to Professor Marvin Burnham, nuclear power will be used as a substitute for natural resources.

6. Many people disagree to use nuclear power as an alternative energy.

7. Radioactivity from nuclear power causes cancer and may have bad effect on the future generations.                  

8. Natural resources should be used as economical as possible.

1……

2……

3……

4……

5……

 

6……

7……

 

8……

 

1
1 tháng 7 2020

1. F

2. F

3. F

4. T

5. F
6.T

7. T

8. T
 

1. Complêt the sentences , using although , despite , in spite of , however , or nevertheless. Sometimes , two answears are possible.1. I think i did OK in my speech last night -------------------- I'd had almost no sleep for 24 hours.2. ---------------------- I heard the telephone ring , I didn't answer it.3. We enjoyed our holiday ------------------- the rain.4. -------------------- he got top marks at high school , he never went to university.5. -------------------------- there was no...
Đọc tiếp

1. Complêt the sentences , using although , despite , in spite of , however , or nevertheless. Sometimes , two answears are possible.

1. I think i did OK in my speech last night -------------------- I'd had almost no sleep for 24 hours.

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

3. We enjoyed our holiday ------------------- the rain.

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

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

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

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

8. Everone thought she would accept the offer . -----------------------, she turned it down.

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

10. It looks like they're going to succeed------------------ their present diffculties.

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

12. My father is very busy.--------------------------, he is always willing to give a hand with the housework.

13. The sky was grey and cloudy .----------------------- , we went to the baech.

14. Some Englis words have the same pronuncation--------------------- they are spell differently , for example , dear and deer.

2. Put question for the underlined part of each sentence: CHỮ IN HOA LÀ PHẦN GẠCH CHÂN NHÉ!

1. I have known Marie FOR NINE YEARS.

2. YES , they used to be friends at the university.

3. Sarah left TWO HOURS  AGO

5. She is watching TOM AND JERRY.

GIÚP MK VS , MK ĐANG CẦN RẤT GẤP , MAI MK PHẢI NỘP BÀI RỒI . HELP ME!!!!!!!

4
17 tháng 4 2017

Righttttttt, we're in math class not english class

ask somewhere else for help, if u can't find any, then you're f**ked

17 tháng 4 2017

đây là toán nha bạn ,bạn nên đăng bài này vào trang wed https://hocmai.vn/

10 tháng 9 2017

cái gì vậy

10 tháng 9 2017

bạn viết gì vậy ??????

1 tháng 2 2016

Viết TV giùm đi

1 tháng 2 2016

moi trang sach duong tron va hinh tam giac co 3 diem chung ok