Đáp án: Giải phương trình x^(2) +4x+12=0 - [(l) (x^2) + 4x + 12 = 0 ⇔ (x^2) + 4x + 4 + 8 = 0 ⇔ (( (x + 2) )^2) + 8 = 0 Vi (( (x + 2) )^2) ≥ 0 ∀ x ⇒ (( (x + 2) )^2) + 8 > 0 ∀ x ⇒ pt da cho vo nghiem ]

[(l) (x^2) + 4x + 12 = 0 ⇔ (x^2) + 4x + 4 + 8 = 0 ⇔ (( (x + 2) )^2) + 8 = 0 Vi (( (x + 2) )^2) ≥ 0 ∀ x ⇒ (( (x + 2) )^2) + 8 > 0 ∀ x ⇒ pt da cho vo nghiem ]

^2 + 4x+ 12=0^2 + 4x + 4 + 8= 0( x+ 2)^2 = -8Mà ( x+2)^2 luôn lớn hơn 0 nên pt vô nghiệm

My Nguyễn

3 năm trước

Giải phương trình $x^{2}$ +4x+12=0

Xem đáp án

54 lượt xem

2 câu trả lời

maipham241

3 năm trước

$\begin{array}{l} {x^2} + 4x + 12 = 0\\ \Leftrightarrow {x^2} + 4x + 4 + 8 = 0\\ \Leftrightarrow {\left( {x + 2} \right)^2} + 8 = 0\\ Vi\,\,\,{\left( {x + 2} \right)^2} \ge 0\,\,\,\forall x\\ \Rightarrow {\left( {x + 2} \right)^2} + 8 > 0\,\,\,\forall x\\ \Rightarrow pt\,\,da\,\,cho\,\,vo\,\,nghiem. \end{array}$

li_2k5_old

3 năm trước

X^2 + 4x+ 12=0

X^2 + 4x + 4 + 8= 0

( x+ 2)^2 = -8

Mà ( x+2)^2 luôn lớn hơn 0 nên pt vô nghiệm

Đăng nhập để trả lời

Câu hỏi trong lớp Xem thêm

Câu IX. Hoànchỉnhcâuthứhaisaochokhôngthayđổinghĩa so vớicâuđãcho.(1,2điểm) 1. They changed the date of the meeting. àThe date ____________________. 2. “Did your team win the previous match?” said Bill. à Nam asked 3. We must take steps to preserve natural resources; otherwise the planet will be in danger.  If 4. The last time he played sports was 2 months ago. → He _ 5. I can't cook as well as my mother. => My mother can _ 6. Although Bill took a taxi, he still arrived late for the concert. → Despite____________________________________

1 lượt xem

2 đáp án

1 giờ trước

Câu VIII. Đọcđoạnvănsauvàchọncâutrảlờiđúngchocáccâuhỏi.(0,8điểm) It is often considered that the schoolyard is where bullies go to make other kids a miserable school life, but a new study suggests that classrooms are another popular place. The study, presented recently at the American Public Health Association's yearly meeting in Philadelphia, is based on the results of the research from more than 10,000 middle school students who answered questions online. Of those researched, 43% said they'd been physically bullied within the last month. A bit more than half said they had been laughed atin an unfriendly way, and half reported being called hurtful names. About one third said groups had excluded them to hurt their feelings. 28% said their belongings had been taken or broken; 21% said someone had threatened to hurt them. According to the results, two-thirds of the students said they had been bullied in more than one way over the previous month. The study authors mentioned that 8% of the students who answered said they had missed school at least once during the school year because of fear of being bullied. 25% said they had taken other actions, such as missing recess, not going to the bathroom or lunch, missing classes, or staying away from some area of the school to escape from experiencing a bully. Bullies did too much to the school life. exclude: (v) loại, đuổi recess: (n) giờgiảilao, giờrachơi make fun of: đùacợt, chếnhạo, giễu = laugh at 1. Which of the following is probably the best title for the passage? A. Bad School Life B. Bullies at School C. Fear at School D. School Problems 2. What does the word "they" in the passage refer to? A. authors B. researchers C. students D. groups 29. The underlined phrase ‘‘laughed at” in the passage is closest in meaning to_______ A. made fun of B. smiled nicely C. shouted at D. looked after well 30. Which of the following might some students do to protect themselves from bullies? A. They miss school. B. They call their parents for help, C.They try to hurt others. D. They break others' belongings.

1 lượt xem

1 đáp án

1 giờ trước

Look! The sun quickly (disappear)...................................behind a cloud giải thích chi tiết nhé

2 lượt xem

1 đáp án

1 giờ trước

Câu VII. Đọcđoạnvănsauvàtrảlờicáccâuhỏi.(0,8điểm) Solar energy is a long lasting source of energy which can be used almost anywhere. To generate solar energy, we only need solar cells and the sun! Solar cells can easily be installed on house roofs, so no new space is needed and each user can quietly generate their own energy. Compared to other renewable sources, they also possess many advantages. Wind and water power rely on turbines which are noisy, expensive and easy to break down. Solar cells are totally silent and non-polluting. As they have no moving parts, they require little maintenance and have a long lifetime. However, solar energy also has some disadvantages. We can only generate solar energy during daytime because the system depends on sunlight. Besides, solar cells require large area to work effectively. The main disadvantage of solar energy is that it costs about twice as much as traditional sources such as coal, oil, and gas. This is because solar cells are expensive. Scientists are hoping that the costs of solar cells will reduce as more and more people see the advantages of this environmentally friendly source of energy. 1. Where can we install solar cells to generate solar energy: on house floor or the house roofs? 2. What are the disadvantages of wind and water power? 3. Do solar cells require much maintenance? 4. Which is more expensive, solar energy or traditional sources of energy?

2 lượt xem

1 đáp án

1 giờ trước

Choose the best answer.
I think you should buy ___ pack of mineral water instead. And you can also buy _ snacks such as potato crisps, 3 kilos of mandarins, 2 kilos of apples, 3 bunches of bananas, ____ cookies and soft candies.

428

428 lượt xem

1 đáp án

2 năm trước

Choose the best answer.
We should decorate our living room with _ orange banner. We also need ____ ribbons, balloons, party hats and costume.

344

344 lượt xem

1 đáp án

2 năm trước

Choose the best answer.
I think that ______ cauliflower is not enough for 3 people. Let’s buy one more.

331

331 lượt xem

1 đáp án

2 năm trước

Giải phương trình $x^{2}$ +4x+12=0

2 câu trả lời

Look! The sun quickly (disappear)...................................behind a cloud giải thích chi tiết nhé

Choose the best answer.
I think you should buy ___ pack of mineral water instead. And you can also buy _ snacks such as potato crisps, 3 kilos of mandarins, 2 kilos of apples, 3 bunches of bananas, ____ cookies and soft candies.

Choose the best answer.
We should decorate our living room with _ orange banner. We also need ____ ribbons, balloons, party hats and costume.

Choose the best answer.
I think that ______ cauliflower is not enough for 3 people. Let’s buy one more.

Đề thi - đề kiểm tra Xem thêm

Chúng tôi

Học tốt

Liên kết

Mạng xã hội

Giải phương trình x2x^{2} +4x+12=0

2 câu trả lời

Look! The sun quickly (disappear)...................................behind a cloud giải thích chi tiết nhé

Choose the best answer.I think you should buy _____ pack of mineral water instead. And you can also buy _____ snacks such as potato crisps, 3 kilos of mandarins, 2 kilos of apples, 3 bunches of bananas, ______ cookies and soft candies.

Choose the best answer.We should decorate our living room with _____ orange banner. We also need ________ ribbons, balloons, party hats and costume.

Choose the best answer.I think that ______ cauliflower is not enough for 3 people. Let’s buy one more.

Đề thi - đề kiểm tra Xem thêm

Giải phương trình $x^{2}$ +4x+12=0

Choose the best answer.
I think you should buy ___ pack of mineral water instead. And you can also buy _ snacks such as potato crisps, 3 kilos of mandarins, 2 kilos of apples, 3 bunches of bananas, ____ cookies and soft candies.

Choose the best answer.
We should decorate our living room with _ orange banner. We also need ____ ribbons, balloons, party hats and costume.

Choose the best answer.
I think that ______ cauliflower is not enough for 3 people. Let’s buy one more.