Đáp án:
Giải thích các bước giải:
`x/y=3/4`
`⇒ x/3=y/4`
`⇒ {-3x}/{-9}={5y}/{20]={-3x+5y}/{-9+20}`
Vì $-3x+5y=33$ nên
`{-3x}/{-9}={5y}/{20]={33}/{11}=3`
$⇒x=9 , y=12$
Đáp án: `x=9;y=12`
`x/y=3/4 <=> 4x=3y <=> x/3=y/4<=> (-3x)/(-9) = (5y)/20 `
Áp dụng tính chất của dãy tỉ số bằng nhau có:
`(-3x)/(-9) = (5y)/20=(-3x+5y)/(-9+20) = 33/11=3`
`=>x/3=3<=>x=3.3=9`
`y/4=3<=>y=3.4=12`
8.5 : Số liệu nào dưới đây phù hợp với 1 h/s THCS ? A. Khối lượng 400g B. Trọng lượng 400N C. Chiều cao 400mm D. Vòng ngực 400cm
21. You _______ spend all your time playing computer games when you’ve got exams next week. A. had not better B. ought to C. had better not D. have got to 22. "Would you pick the kids up from school this afternoon?" "No, I’m afraid I _______ " A. wouldn’t B. shan’t C. don’t D. can’t 23. Profits _______ slightly next year, although we don’t predict any job losses. A. are expected to fall B. are expecting to fall C. expect to fall D. are expected falling 24. It’d be great to see you on Sunday evening _______ you’ve already got other plans. A. unless B. otherwise C. as long as D. provided 25. A significant number of students decide _______ for a Master’s degree to enhance their knowledge. A. as to study B. as though study C. to study D. for studying 26. In many _______ of music, some kind of drum is used to provide the rhythm. A. sets B. types C. notes D. records 27. The music was really quite boring and had no real _______ A. flash B. light C. luster D. shine 28. Sometimes a piece of music can _______ very strong memories and emotions. A. evoke B. provoke C. speak D. talk 29. The influence of social media is so great that actors can be _______ to superstar status almost overnight. A. lifted B. improved C. elevated D. raised 30. It would have been a great journey _______ we not got lost along the way. A. might B. should C. would D. had
nếu ý nghĩa cảu việc phatrien Nông-lâm-ngư-nghiệp
Nhà nước đã thực hiện biện pháp nào để ổn định hệ thống chính quyền và hệ thống chính trị của đại thắng mùa xuân 1975
Viết đoạn văn tiếng anh nói về những thuận lợi về cuộc sống vùng nông thôn
Viết đoạn văn biểu cảm về mẹ (7 đến 12 dòng )
Giúp mình mấy câu cuối nf trống đó với
11. One of the most important skills is to _______ to make use of your time effectively. A. learn B. alter C. continue D. adapt 12. The writers of smash _______ "Stranger Things" have confirmed that the scripts for the fourth season are complete. A. coverage B. trailer C. hit D. print 13. Although he never graduated _______ high school, he became a successful businessman. A. to B. from C. at D. with 14. The show climaxed with all the performers singing _______ stage together. A. by B. at C. on D. off 15. What do you _______ to gain from the course? A. yearn B. incline C. hope D. favour 16. We were asked to show some identification before the security guards would _______ us in. A. authorize B. let C. leave 17. I’d love _______ afford to take a month or two off. A. to can B. that I will C. I could D. to be able to 18. New and innovative music had a great _______ on young people and the whole Britain became less conservative. A. progress B. innovation C. influence D. substitute 19. Since we got _______ we’ve been watching music videos online. A. resource B. data C. program D. broadband 20. Have you _______ the blank CDs I gave you, or have you got some left? A. done up B. used up C. mixed up D. backed up
Làm cho mình với cái nào đúng thì để lại
Hãy nếu các lợi ích của ti vi cảm ứng trong học tập
Loga.vn - Cộng Đồng Luyện Thi Trực Tuyến