Lửa không có công thức hoá học vì lửa không phải một chất hoá học cụ thể

Do 1 > 0

\(\left|x\right|\ge0\)

\(\Rightarrow1+\left|x\right|>0\)

Do đó \(1+\left|x\right|=-2\) là điều vô lý

\(\Rightarrow\) Không tìm được \(x\) trong trường hợp này

Vậy bài của em là sai

1. Hạnh won the first prize because she worked hard.

Because of working hard, Hanh won the first prize

2. What is the distance between the cinema and your school?

How far is it from the cinema to your school?

3. Because she is beautiful, everyone looks at her. (so)

She is beautiful, so everyone looks at her

4. Hoa loves classical music, but her brother loves rock music. (different)

Hoa’s favorite kind of music is different from her brother's

5. It’s a good idea to do exercise every day.

We should exercise everyday

6. Mary doesn’t live in the countryside any more.

Mary used ______________to live in the countryside____________________________________________.

7. Remember to wake me up at 7 tomorrow morning.

Don’t ____forget to wake me up at 7 tomorrow morning______________________.

8. Watching TV is more interesting than reading books.

 I prefer watching TV to reading books

9. She enjoys reading more than watching television.

She is _____more interested in reading than in watching television_____________________.

10. We won't go camping if it rains tomorrow.

Unless it rains tomorrow, we will go camping

11. His new school is bigger than his old school.

His old school isn’t …as big as his new school………………………………………………….

12. This room is larger than the one in the corner of the museum.

The room in the corner of the museum isn’t as large as this room

13. The red car is bigger than the black one. (AS)

The black car is not as big as the red car

14. It is not necessary for you to finish your work today. (HAVE)

You don't have to finish your work today

15. If you don’t take care of your books, they won’t last for long. (UNLESS)

Unless you take care of your books, they won't last for long

16. I don’t like fried chicken. However, everybody else seemed to enjoy it. (ALTHOUGH)

Everybody else seemed to enjoyed fried chicken although I don't like it

17. I walk to school in 20 minutes (TAKES)

It takes me 20 minutes to walk to school

18. It takes me 50 minutes to do this math exercise. (SPEND)

I spend 50 minutes doing this math exercise

19, I played football when I was young. (USED)

I used to play football when I was young

20. It’s a good idea to do eat healthy food. (SHOULD)

You should eat healthy food

a. M(x) =  x² + 2x – 3 + x² - 9x + 5

= 2x² - 7x + 2

N(x) =  x² + 2x – 3 - x² + 9x - 5

= 11x - 8

\(A=x(x-1)-x+13\\=x^2-x-x+13\\=(x^2-2x+1)+12\\=(x-1)^2+12\)

Ta thấy: \(\left(x-1\right)^2\ge0\forall x\)

\(\Rightarrow\left(x-1\right)^2+12\ge12\forall x\Rightarrow A\ge12\forall x\)

Dấu \("="\) xảy ra khi: \(x-1=0\Leftrightarrow x=1\)

Vậy \(Min_A=12\) tại \(x=1\).

Kiến trúc Ấn Độ chịu ảnh hưởng sâu sắc của ba tôn giáo lớn là:Phật giáo,Hin-du giáo và Hồi giáo.

Đặt \(\dfrac{a}{b}=\dfrac{b}{c}=\dfrac{c}{d}=\dfrac{d}{a}=k\)(k<>0)

=>\(\left\{{}\begin{matrix}d=a\cdot k\\c=d\cdot k=a\cdot k\cdot k=ak^2\\b=ck=ak^3\\a=bk=ak^4\end{matrix}\right.\)

\(a=ak^4\)

=>\(ak^4-a=0\)

=>\(a\left(k^4-1\right)=0\)

=>\(k^4-1=0\)

=>\(\left[{}\begin{matrix}k=1\\k=-1\end{matrix}\right.\)

\(M=\dfrac{3a+b}{5b-d}+\dfrac{2b+3c}{2d-b}\)

\(=\dfrac{3\cdot ak^4+ak^3}{5\cdot ak^3-ak}+\dfrac{2\cdot ak^3+3\cdot ak^2}{2\cdot ak-ak^3}\)

\(=\dfrac{ak^3\left(3k+1\right)}{ak\left(5k^2-1\right)}+\dfrac{ak^2\left(2k+3\right)}{ak\left(2-k^2\right)}\)

\(=\dfrac{k^2\left(3k+1\right)}{5k^2-1}+\dfrac{k\left(2k+3\right)}{2-k^2}\)

TH1: k=1

=>\(M=\dfrac{1^2\left(3\cdot1+1\right)}{5\cdot1^2-1}+\dfrac{1\left(2\cdot1+3\right)}{2-1^2}=\dfrac{4}{4}+\dfrac{5}{1}=6\)

TH2: k=-1

=>\(M=\dfrac{\left(-1\right)^2\cdot\left(-3+1\right)}{5\cdot\left(-1\right)^2-1}+\dfrac{\left(-1\right)\left(2\cdot\left(-1\right)+3\right)}{2-\left(-1\right)^2}\)

\(=\dfrac{-2}{4}+\dfrac{1}{1}=-\dfrac{1}{2}+1=\dfrac{1}{2}\)

cíu tuii  

ghép câu thành có nghĩa: H/ồ/g/.../B/a/o/n

Lê Hoàn lập nên nhà Tiền Lê,đổi niên hiệu là Thiên Phúc.

Thiên Phúc

Lê Hoàn mất năm 1005.Người nối ngôi tiếp là Lê Đại Hành

Năm 1005,Lê Hoàn mất.Lê Long Đĩnh nối ngôi.