$P=x^2+10x+28$
$= x^2+10x+25+3$
$= (x+5)^2+3$
Vì $(x+5)^2\ge 0\; \forall x$
$\to (x+5)^2+3\ge 3\; \forall x$
Vậy $\min P=3$ khi $x+5=0 ↔ x=-5$
~ Bạn tham khảo ~
Ta có :
`P = x^2 + 10x + 28`
`=> P = x^2 + 10x + 25 + 3`
`=> P = (x^2 + 2.5.x + 5^2) + 3`
`=> P = (x+5)^2 + 3` (Áp dụng HĐT số 1)
Vì `(x+5)^2>=0`
`=> P >= 3`
Dấu "=" xảy ra `<=> (x+5)^2=0`
`<=> x+5=0`
`<=> x=-5`
Vậy `P_min = 3 <=> x = -5`
Mọi người giúp mik với ( vẽ hình và giải)
phân tích thành nhân tử( phương pháp dùng hằng đẳng thức) 33, (4a+3b)^2-(b-2a)^2 34, (2a-b)^2-4(a-b)^2 35, 4(2a-b)^2-16(a-b)^2 36, 81(x+7)^2-(3x+8)^2 37, x^2+10x+25 38, 4x^2+12x+9 giai chi tiết giúp mk với ạ
Giúp mik với ạ Mik đanh cần gấp
1. What is your favorite subject? → What subject 2. There are 35 students in my class. → My class 3. Mai live near her school. → Mai’s house isn’t 4. Mary plays the piano very well. → Mary is good 5. Do you like physics? → Are you interested 6. The school has a computer room and a library. → There
VIII. Read the passage below and write T(True) and F(False): It’s six o’clock in the evening. Many people are at home. They are having dinner. They are watching TV. They are listening to music. But Mrs.Bich is going to work. She’s a doctor and she works at night in the hospital. Today she’s late. The hospital is not in her neighborhood so she usually goes by car. Mrs Bich is in her car now. She’s driving fast. She should slow down but she must at work by six thirty. A policeman stops her. “You are driving too fast!” he says. You are going to have an accident. It’s six tirty. Mrs Bich is not at the hospital. She is at the police station. Her car must stay there for fourteen days. 1.____________Many people are not working. 2.____________Mrs Bich comes home every evening at six. 3.____________Mrs Bich is a night doctor. 4.____________The hospital is near her house. 5.____________She goes to work by motorbike. 6.____________She is late for work. 7.____________She is a dangerous driver. 8____________A police man doesn’t keep her car. 9.___________She drives at the hospital at 6.30. 10.__________She isn’t going to drive her car for two weeks.
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