Đáp án:
PT:`ax^2+bx+c=0(a ne 0)`
PT bậc 2 có đúng 1 nghiệm dương,1 nghiệm âm có nghĩa là phương trình có 2 nghiệm trái dấu.
`<=>a.c<0`
phương trình bậc 2 có dạng $ax^2+bx+c=0(a$$\neq0)$
Để phương trình có 2 nghiệm trái dấu $⇔P<0$
Trong đó $P=x_1x_2=\dfrac{c}{a}$
Giúp mình bài này vs ạ Mình đg cần gấp 🙏🏼🙏🏼
Tìm x, biết: x³ - 7x² = 7 - x Làm theo phương pháp đặt nhân tử chung nha.
Người ta đào một cái giếng hình trụ có bán kính 60cm và có độ sâu là 10m. a) Hãy tính thể tích của cái giếng (kết quả làm tròn đến chữ số thập phân thứ nhất). b) Đất, khi được lấy lên thì thể tích của nó nở thêm 20% nữa. Đất đào lên được chuyển đến vị trí khác bằng các xe tải có thể chở được mỗi chuyến 3m^2 đất. Hỏi phải cần bao nhiêu chuyến xe tải như thế? (Chú ý: Cho biết pi = 3,14. Thể tích của hình trụ bằng diện tích đáy nhân với chiều cao). Hộ em bài này vớiiiiiii Chi tiết dễ hiểu ạ!!!
THứ tôi cần là đáp án và giải thích
đề bài : tả bác hồ viết bài văn ạ ngắn nửa trang giấy nhé
giúp mik vs ạ mik cảm ơn ( mn ko cần giải thích đâu ạ vì mik đang cần gấp )
Giúo mình hai bài Ở dưới nha , nhanh nhé
a.Cho mạch như hình dưới đây. Điện trở tương đương của mạch điện là…..Ω b.Cho mạch như hình dưới đây. Hiệu điện thế toàn mạch là…..V
5. Choose the best answer to complete each of the following sentences. 1. Last week, he told us that we a picnic at the end of the week on Friday. A. can have B. did have C. would have D. had had 2. Four days ago she promised that she was going to visit me but she didn’t arrive. A. tomorrow B. next day C. the day before D. the next day 3. When I met her, she admitted that she to the park the night before. A. went B. had gone C. was going D. did go 4. When asked by the teacher, all students said they literature. A. liked B. are liking C. were liking D. had like 5. When I phoned him, he told me that he in the garden, reading a newspaper. A. sat B. was sitting C. had sat D. has sat 6. When I saw her, she told me that she hadn’t come to the party because she had gone to the embassy in London. A. yesterday B. before day C. the before day D. the day before 7. He called the school and said that he to school because he had an accident. A. didn’t come B. couldn’t come C. doesn’t come D. wasn’t come 8. My close friend told me that he studying in America. A. likes B. liked C. had liked D. was liking 9. When we asked her about the film, she told us that she a more interesting film than that. A. never saw B. never seen C. had never seen D. did never see 10. Diana told us that she was going to visit boyfriend in Rome the next week and wouldn’t come to class. A. my B. her C. your D. their 11. He wanted to know where she from. A. come B. coming C. to come D. came 12. I asked her to pursue higher studies the next year. A. are you planning B. if she is planning C. was she planning D. if she was planning 13. I asked her when A. the movie began B. the movie begins C. does the movie begin D. did the movie begin 14. I promised I there before she came back. A. am going to be B. was going to be C. will be D. can be 15. Peter asked her, “Have you got a laptop?” → Peter asked her a laptop. A. if she got B. if she had got C. whether she got D. whether had she got 16. My mother told me her up at the airport. A. please pick B. to pick C. should pick D. I can pick 17. He revealed that they married A. were getting - tomorrow B. are getting - the next day C. were getting - the next day D. will getting - the day after 18. He wanted to know when A. did I arrive B. will I arrive C. I had arrived D. I can arrive 19. The father said, “I didn’t see her.” → The father said her. A. he had seen B. I hadn’t seen C. she didn’t see D. he hadn’t seen 20. I wondered the right thing. A. if I am doing B. was I doing C. am I doing D. whether I was doing
Cmr khi m thay đổi thì đường thẳng (d) có ptrinh 2x(m+4) + ( m-1)y =m luôn đúng qua 1 điểm cố định
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