Thay x^2=4 vào biểu thức

Sau đó xét 2 trường hợp x=2 và x=-2

\(\left|x\right|=2\Rightarrow\orbr{\begin{cases}x=2\\x=-2\end{cases}}\)

Khi x = 2 thì \(5x^2-2x+3x-1=5.2^2-2.2+3.2-1=20-4+6-1=21\)

Khi x = -2 thì \(5x^2-2x+3x-1=5.\left(-2\right)^2-2.\left(-2\right)+3.\left(-2\right)-1\)

                                                           \(=20+4-6-1=17\)

I:

1. C

2. B

3. C

4. B

5. A

II:

1. A

2. D

4. B

5. A

I. Nội qui tham gia "Giúp tôi giải toán"

1. Không đưa câu hỏi linh tinh lên diễn đàn, chỉ đưa các bài mà mình không giải được hoặc các câu hỏi hay lên diễn đàn;

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II. Cách nhận biết câu trả lời đúng

Trên diễn đàn có thể có rất nhiều bạn tham gia giải toán. Vậy câu trả lời nào là đúng và tin cậy được? Các bạn có thể nhận biết các câu trả lời đúng thông qua 6 cách sau đây:

1. Lời giải rõ ràng, hợp lý (vì nghĩ ra lời giải có thể khó nhưng rất dễ để nhận biết một lời giải có là hợp lý hay không. Chúng ta sẽ học được nhiều bài học từ các lời giải hay và hợp lý, kể cả các lời giải đó không đúng.)

2. Lời giải từ các giáo viên của Online Math có thể tin cậy được (chú ý: dấu hiệu để nhận biết Giáo viên của Online Math là các thành viên có gắn chứ "Quản lý" ở ngay sau tên thành viên.)

3. Lời giải có số bạn chọn "Đúng" càng nhiều thì càng tin cậy.

4. Người trả lời có điểm hỏi đáp càng cao thì độ tin cậy của lời giải sẽ càng cao.

5. Các bài có dòng chữ "Câu trả lời này đã được Online Math chọn" là các lời giải tin cậy được (vì đã được duyệt bởi các giáo viên của Online Math.)

6. Các lời giải do chính người đặt câu hỏi chọn cũng là các câu trả lời có thể tin cậy được.

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cô giáo kiểm tra mà cần gấp đúng ngáo nặng mà

Tham khảo

There is a famous animated film that I think everyone of us has seen at least once, and it is Tom and Jerry. Almost everyone is aware of the story between the miserable Tom and the mischievous mouse Jerry, and it also was part of my childhood memories. The film is about a life under the same roof between two enemies Tom and Jerry, and of course cat and mouse are always hard to get along with. Tom's owner is very afraid mouse, so she always asks Tom to catch the little mouse living in a cave that he digs on the wall. Tom is a quite lazy cat, and he often has to chase Tom so that he is not scolded by his owner or in exchange for a good meal. Sometimes, Jerry also makes mischievous jokes to tease Tom such as pull out his hair or steal his milk. Another character in the movie is the dog Spike, and he does not seem to like Tom at all. In the chasing scenes of the two main characters, they sometimes run to the garden - Spike's residence - and disturb his sleep. Most of the time, Tom would be the one who suffers Spike's anger while Jerry is having a big laugh. The plot is simple but the film Tom and Jerry always attracts a lot of audiences of all ages thanks to the lovely characters and funny circumstances. Although many years have gone by, the television channels have often displayed this film, and this is the indispensable spiritual food children.

Refer

Write about your favourite movie

Today I’d like to talk to you about Harry Porter which is one of my favourite films. It was a fiction film telling a story about people in the wizarding world. The central character was Harry Porter, who used to be an orphan in the normal world before discovering that he was a wizard. Afterwards, he went to a special school called Howard where taught him necessary skills to succeed in wizarding world. He also had to deal with challenges in terms of study, friendship, love and even the fight against dark power.
Harry Porter was recommended as a masterpiece that making me feel curious about it. Moreover, I had read the original novel before, and I really can’t put it down. So I guess the film would be as attractive as the book.
I think the most important reason why I enjoyed this film was that it made me feel adventurous. It was really a fantastic film.

Write about your favourite book

Favorite book and then the series "Doraemon" by Fujiko Fujio. The series told the cat from the future into the past Doremon same friends and help Nobita in the security context miracle. The main character is Doremon with your group Nobita, Shizuka, Xeko, Chaien. Extremely interesting story, engage the reader with the hilarious, witty, and full of magic. But it is also part of suspense through risky adventure of your group. The series is divided into two categories: short stories and novels. I enjoyed the long story, it's about the adventures in a strange land or through time times exciting but dangerous, and the group must go through many difficulties and from there we saw noble friendship bunch of kids. When I read the story I kept imagining myself as the character in that book that I could not put down. And I learned a lot from it especially friendships! If you have not read it try to read offline sure you will like it.

I)1.B

2.B

3.C

4.D

5.C

II)

1.B

2.D

3.B

4.B

5.A

6.B

7.tell....way.

8.C

III)

1.isn't teaching

2.drive

3.has

làm phần nào?

Bạn tham khảo ở đây: Câu hỏi của nyuyen van binh - Toán lớp 6 - Học toán với OnlineMath

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