Đáp án: Giải thích các bước giải:
$ x² - 3x - 40 = 0$
$x² + 5x - 8x - 40 = 0$
$x(x+5) - 8(x+5) = 0$
$(x-8)(x+5) = 0$
\(\left[ \begin{array}{l}x=8\\x=-5\end{array} \right.\)
Đáp án:
Giải thích các bước giải:
`a)` Cho `D(x) = 0`
`=> x^2 - 3x - 40 = 0`
`=> x^2 - 8x + 5x - 40 = 0`
` (x^2 - 8x) + (5x - 40) = 0`
`x(x - 8) + 5(x - 8) = 0`
`(x - 8)(x + 5) = 0`
`=>` $\left[\begin{matrix} x- 8=0\\ x+ 5=0\end{matrix}\right.$
`=>` $\left[\begin{matrix} x=8\\ x=-5\end{matrix}\right.$
Vậy `x = 8` hoặcn`x = -5` là nghiệm của `D(x)`
1. She rarely goes to the cinema at weekend, isn’t she? A B C D 2. She will pay less but she uses to energy- saving bulbs. A B C D 3. She walked ten kilometers a day to get water enough for her family to use. A B C D 4. I have already cleaned the floor, but I still need dusting the furniture. A B C D 5. I knew Tim when he was a child, but I didn’t see him for many years. A B C D 6. A tourist wanted to know whether she take any photos there A B C D 7.They worked in the garden when it started to rain. A B C D 8. Thanks for invite me to your birthday party. A B D D 9. You have never been to Ho Chi Minh City before, haven’t you? A B C D 10. He is not old enough driving motorbike. A B C D
Giúp mình tìm f'(x) với ạ, sách làm tắt mình khong hỉu😢
mik gấp lắm r ạ, giúp mik vs , mik k có time lm
2x:x+5+10x:x^2+5x (với x ko = 0; x ko =5 Thực hiện phép tính
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Mọi người giúp mình 2 câu này với
Dung dịch H2SO4 loãng có thể tác dụng đc với KL trong dãy nào sau đây? A. Mg Fe Al B. Fe ZN Ag C. Mg Zn Hg D. Al Cu Mg
IV. Use the correct form of verbs in brackets. 1. In all the world, there (be) __________ only 14 mountains that (reach) __________above 8,000 meters. 2. He sometimes (come) __________ to see his parents. 3. When I (come) __________, she (leave) __________for Dalat ten minutes ago. 4. My grandfather never (fly) __________ in an airplane, and he has no intention of ever doing so. 5. We just (decide) __________ that we (undertake) the job. 6. He told me that he (take) __________ a trip to California the following week. 7. I knew that this road (be) __________ too narrow. 8. Right now I (attend) __________ class. Yesterday at this time I (attend) __________class. 9. The traffic was very heavy. By the time I (get) __________to Mary’s party, everyone already (arrive) 10. I (visit) __________ my uncle’s home many times when I (be) __________ a child. 11. That book (lie) __________ on the table for week. You (not read) __________ it yet ? 12. David (wash) __________ his hands. He just (repair) __________ the TV set. 13. You (be) __________here before? Yes, I (spend) __________ my holidays here last year. 14. We never (meet) __________ him. We don’t know what he (look) __________ like. 15. The car (be) __________ ready for him by the time he (come) __________tomorrow. 16. On arriving at home I (find) __________that she just (leave) __________a few minutes before. 17. Last night we (watch) __________TV when the power (fail) __________. 18. London (change) a lot since we first (come) __________ to live here. 19. While we (talk) __________on the phone the children (start) __________fighting and (break) __________a window 20. I (spend) __________ a lot of time travelling since I (get) __________this new job.
Chứng minh: Hình thang có 2 đường chéo bằng nhau là hthang cân. C/m: giùm mình gấp nhé. Vẽ hình luôn nha
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