Để $x+x^2\sqrt{\dfrac{21-3x}{x^2+6}}$ xác định
`<=>{({21-3x}/{x^2+6}>=0),(x^2+6\ne0):}`
`<=>{(21-3x>=0),(x^2\ne-6(luôn đúng)):}`
`<=>-3x>=-21`
`<=>x<=7`
Vậy $x\le7$ thì $x+x^2\sqrt{\dfrac{21-3x}{x^2+6}}$ xác định
`\qquad x+x^2\sqrt{(21-3x)/(x^2+6)}`
ĐKXĐ: `(21-3x)/(x^2+6)>=0`
`=> 21-3x>=0` (do `x^2+6>0` với `AAx`)
`<=> 3x<=21`
`<=> x<=7`
Vậy `x<=7` thì căn thức đã cho xác định.
Giúp mình bài này ạ~~~ 1. The…..war soon spread nationwide. (independent / independence / dependable / dependence) 2. This ticket…..one person to the museum. (allows / permits / enters / admits) 3. He…..us but he was short of money then. (can help / could have helped / would help / might help) 4. …..considered a promising writer, she hasn’t been successful. (Despite / In spite / Though / As) 5. Bill's a lucky fellow, he always seems to fall on his….. (legs / feet / ankles / hands) 6. The picture was sold for a great…..of money. (cost / sum / value / price) 7. Shall we…..our journey in Paris and continue the next day? (stop / break / pause / interrupt) 8. Susie goes to bed at exactly 10.30 every night; she's a…..of habit. (creature / species / breed / piece) 9. All their money is…..up in the house they have bought. (connected / trapped / limited / tied) 10. We found some real…..at the sale. (prizes / items / goods / bargains) 11. The meteorologists say we're likely to have a…..winter this year. (calm / soft / mild / smooth) 12. I…..it’ll rain this afternoon. (bet / promise / warn / vow) 13. The pool should not be so deep…..small children can be safe there. (as if / so as / even if / so that) 14. She…..regretted having been so unkind. (awfully / bitterly / severely / fully) 15. We…..all your help in this matter. (estimate / enjoy / appreciate / evaluate)
c. 7 8/(1000 ) và 7 6/(1000 )
Câu 14 chọn j ạ Chỉ cần đáp án
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Phân chia các danh từ sau thành danh từ đếm được và danh từ không đếm được Person, smoke, water, sugar, car, tomato, dog, tea, apple, class, beer, soup, doctor, butter, cheese, housework, pen, cup, bread, happiness, bus, map, help, information, book, orange, window, advice, boy, hair, news, box, piano, leaf
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Giúp em đặt câu - Viết 6 câu, sử dụng 6 động từ trong bài tập D trang 35 (sách học sinh) và liên từ 'but',
Mark the letter A, B, C, or D to indicate the words(s) CLOSEST in meaning to the underlined words(s) in each of the following questions. Question 15: There is not a lot of world news in this newspaper. A. crowded B. international C. urban D. local Question 16: At weekends the city is always packed with people. A. crowded B. busy C. noisy D. polluted Mark the letter A, B, C, or D to indicate the words(s) OPPOSITE in meaning to the underlined words(s) in each of the following questions. Question 17: A small fish needs camouflage to hide itself so that its enemies cannot find it. A. cover B. beautify C. show D. locate Question 18: Solar energy doesn't cause pollution, but it is not cheap. A. expensive B. effective C. commercial D. possible Mark the letter A, B, c, or D to indicate the most suitable response to complete each of the following exchanges. Question 19: Jim: “What about collecting used paper, bottles and plastic bags every day?’" Ha and Mai: “ A. Because they can pollute the environment. B. How come? Who can do that? C. That's a very good idea. Let's do that. D. What about this weekend? Question 20: Phuong: “I'm taking my TOEFL test tomorrow.” Daisy: “ ” A. Good fortune. B. Good luck. C. Good outcome. D. Good success.
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điền đúng hay sai a, 1 mũ 3 =+ 2 mũ 3 + 3 mũ 3= ( 1+2+3) mũ 2
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