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8 tháng 8 2017

1. \(\dfrac{4x}{4x^2-8x+7}+\dfrac{3x}{4x^2-10x+7}=1\)

Dễ thấy \(x=0\) ko phải là nghiệm của pt

Chia tử và mẫu cho x, ta được:

\(\dfrac{4}{4x-8+\dfrac{7}{x}}+\dfrac{3}{4x-10+\dfrac{7}{x}}=1\) (*)

Đặt \(t=4x+\dfrac{7}{x}-8\) thì:

(*) \(\Rightarrow\dfrac{4}{t}+\dfrac{3}{t-2}=1\)

Quy đồng lên tìm được t, sau đó dễ dàng tìm được x.

8 tháng 8 2017

2 bài kia tương tự bạn nhé, cũng chia tử và mẫu cho x rồi đặt ẩn phụ

Bài 2 đặt \(t=x+\dfrac{15}{x}\)

Bài 3 đặt \(t=x+\dfrac{3}{x}\)

31 tháng 10 2021

Bạn tách bớt ra nhé!

31 tháng 10 2021

là phải chụp từng câu 1 ạ?

 

31 tháng 10 2021

Đề bài đâu rồi ạ, có đề mới giải được ạ

7 tháng 3 2021

8. As it is raining heavily, we can't go on a picnic

9. I suggest (that) you should get a plumber to check the pipes

10. If you don't succeed, you'll have to try it again

11. If she had enough money, she would buy the dictionary

12. I suggest using gas instead of burning coal

13. I suggest you should install a burglar alarm in your house

14. If we recycle, we will save natural resources

15. If you don't hurry up, you will be late for work

16. If you work too much, you will be tired

17. I suggest putting different kinds of.....

18. Lan broke the glass as she was careless

19. If you litter the place around you, it will be a junk yard

20. Paul suggested using public transportation

21. If she doesn't reduce the use of water and electricity, she will have to.....

22. Since the weather was snowy, we postponed our soccer match

23. Tan suggested that Lam should buy a car

24. Lan suggested that I should look for another job

25. The scientist suggested using public transportation instead of private vehicles

26. giống c12

27. The principle is pleased that the students in grade 9 are good helpers

28. If we put garbage into the bins, we will minimize pollution

29. If you are careless, you will broke the vase

30. If you don't stop cutting trees, I will call the police

31. If you use electricity to catch fish, you will be fined heavily

32. I'm sure that that boy will have a test.....

33. We are disappointed that you threw the rubbish on the street

34. It is extremely important that all of us work together to protect the environment

35. I'm sorry that I couldn't do anything to help you

36. He is sure that environmental pollution in this area can be controlled

37. She was annoyed that he damaged the car yesterday

11 tháng 5 2021

Currently, the development of COVID-19 is very complicated, so students are away from school and living at home to prevent infection. We often spend a lot of time together during the school year, so it is imperative that wash your hands often, especially before eating, after blowing your nose, and after using the toilet. And more importantly, we should wear a mask when recommended by the school and authorities and should be worn properly. We have to make a correct minimum distance of 1.5 m with people. Airborne respiratory viruses exist in saliva droplets when someone sneezes or coughs. So cover your nose and mouth when you sneeze or cough with a tissue or cough and sneeze into your elbow. We love to share utensils, favorite toys and cups with friends, but do not share eating utensils with friends, especially during flu season and other respiratory illnesses. It is important to comply in order to best prevent the Covid-19 epidemic.

11 tháng 5 2021

Passage?

6 tháng 12 2021

Mn làm giúp mk nha,mk đang cần gấp.

a: Xét tứ giác ABNC có 

O là trung điểm của AN

O là trung điểm của BC

Do đó: ABNC là hình bình hành

mà \(\widehat{BAC}=90^0\)

nên ABNC là hình chữ nhật

27 tháng 12 2021

=>KCl2

 =>  CuCl2

2Al+3Cl2=>2AlCl3

 

 

 

       

27 tháng 12 2021

2Al+H2SO4=>3H2+Al2(SO4)3

C9H20+14O2=>10H2O+9CO2

6 tháng 8 2017

1)x^4+x^2-6x+1=0>>>x^4+4x^2+4-3x^2-6x-3=0>>>(x^2+2)^2=3(x-1)^2.

>>Sau đó giải bt.

2)Đặt x^2-x+1=a;x+1=b thì:x^3+1=ab.

Pt:2a+5b^2+14ab=0(tự giải nha)