Tìm x : 1, ( 2x+1)^ 2 -4 (x+1) =3 2, 3 (x-1)( x+1) -2 ( x+1)^2-( x-1)^2 =0 3, (3x-1)^2 + ( 2 +x)^2-10 ( x-2) ( x+2) =0

buithilananh13

2 năm trước

Loga Sinh Học lớp 12

0 lượt thích 23 xem

1 trả lời

Thích Trả lời

KimNgoc

$a)( 2x+1)^ 2 -4 (x+1) =3$

$⇔4x^2+4x+1-4x-4=3$

$⇔4x^2=6$

$⇔x^2=\dfrac{3}{2}$

$⇔x=\dfrac{\sqrt[]{6}}{2}$ hay $x=-\dfrac{\sqrt[]{6}}{2}$

$b) 3 (x-1)( x+1) -2 ( x+1)^2-( x-1)^2 =0$

$⇔3(x^2-1)-2(x^2+2x+1)-(x^2-2x+1)=0$

$⇔3x^2-3-2x^2-4x-2-x^2+2x-1=0$

$⇔-2x=6$

$⇔x=-3$

$ c)(3x-1)^2 + ( 2 +x)^2-10 ( x-2) ( x+2) =0$

$⇔9x^2-6x+1+4+4x+x^2-10(x^2-4)=0$

$⇔9x^2-10x^2+x^2-6x+4x+1+4+40=0$

$⇔-2x=-45$

$⇔x=\dfrac{45}{2}$

Vote (0) Phản hồi (0) 2 năm trước

gialinh

Đáp án + Giải thích các bước giải:

$1.(2x+1)^2-4(x+1)=3$

$⇔(2x)^2+2.2x.1+1^2-(4x+4)=3$

$⇔4x^2+4x+1-4x-4=3$

$⇔4x^2=6$

$⇔x^2=\dfrac{3}{2}$

$⇔x=±\dfrac{\sqrt6}{2}$

Vậy `x∈{\frac{\sqrt6}{2};-\frac{\sqrt6}{2}}`

$2. 3(x-1)(x+1)-2(x+1)^2-(x-1)^2=0$

$⇔3(x^2-1)-2(x^2+2x+1)-(x^2-2x+1)=0$

$⇔3x^2-3-2x^2-4x-2-x^2+2x-1=0$

$⇔-2x=6$

$⇔x=-3$

Vậy `x∈{-3}`

$3. (3x-1)^2+(2+x)^2-10(x-2)(x+2)=0$

$⇔(9x^2-6x+1)+(x^2+4x+4)-10(x^2-4)=0$

$⇔9x^2-6x+1+x^2+4x+4-10x^2+40=0$

$⇔-2x=-45$

$⇔x=\dfrac{45}{2}$

Vậy `x∈{\frac{45}{2}}`

Vote (0) Phản hồi (0) 2 năm trước

Các câu hỏi liên quan

Cho x>0,y>0 TM xy=6. Tìm GTNN của biểu thức: Q=2/x+3/y+6/(3x+2y)

giải giúp mình 2 bài này với ạ tại mình hết điểm rồi í cảm ơn nhé

So sánh 2 số A và B biết A =( 2+1) ( 2^2 +1) ( 2^4+1) và B = 2^8

Sao lại thành ra như thế này, tui đã quyết là sẽ bỏ nick này rồi mà :(( Đề: Vẽ anime vui :)

cos(2x+pi/4)=-1/3 Giải giúp mình với

Mọi người ơi giúp e vơi ạ :> 1. She (go)……………. to school everyday. 2. There (be)………… big problems in many parts of the world. 3. A lot of people (go)………………..to work by car. 4. Davis never (not/take) …………………..the bus to school. 5. He plays volleyball but he (not/enjoy)…………………………..it. 6. Most shops usually (open)…..…… at 8.00 a.m and (close) ………at 6.00 p.m. 7. School children (wear)…………… uniform on Monday. 8. I want ( buy)……………………some stamps. 9. Ruth (live)………………. with his parents in an apartment. 10. He (visit)…………….his parents next week. 11. Lan often (go) ………………. to school on foot? 12. She ……………….(go) to school everyday. 13. Bad students never (work) ……………….hard. 14. The teacher always (point) ……………….at the black – board when he wants (explain) …………..……….something. 15. Her mother always (cook) ………….in the morning? 16. My father (call)………….…..you in 10 minutes. 17. He (meet) ………………….…….. the dentist next week. 18. They usually (not/go) ……………..…..……. to school by motorbike. 19. She (come) ……………..here next month. 20. They (not/be) ……………….. doctors. 21. He often (get) ……………………… up late. 22. You often (watch) …………….TV? 23. His children always (be)……..………….at home. 24. Hai often (wash) ……………………his face at 6.15. 25. Thanh and Mai always (see) ……………………a movie on Saturday. 26. He often (take) ……………………a bus to school? 27. The people (be) ……………students in class 8A. 28. Do you fancy (go)………………out tomorrow? 29. She (go) ……………………to work by bus tomorrow. 30. You (be) ……………………at home tomorrow morning? 31. They sometime(do) …………………morning exercises at 5. 32. Where they (plant) ……………trees next month? 33. Hung (run) …………………about 5 km every morning. 34. He (write) ……………………to his friend next week. 35. Mai and Nam (go) ……………………to the movie theater tomorrow evening. 36. I often (not/wash) ………………my clothes. 37. He often (pick) ………………his friend up at the rain way station morning. 38. What time they(talk) ………………to each other? 39. The sun (rise) …………in the East and (set) …………. in the West. 40. Where she (buy)……………her breakfast every morning? 41. Ngoc (love)…………. cartoons, but she says she (not/continue)…………….. this hobby in the future. 42. There (be)…………………a lot of milk in the bottle. 43. You (do)……………. morning exercise every day? 44. Hoa still (play)………………… badminton next year? 45. My dad loves (go)…………….to football games. 46. I think 10 years from now more people (enjoy)………………. gardening. 47. What your brother (do)………………… in his free time? 48. Tung’s never liked (swim)………………….. 49. If it rains, we (stay)……………..at home. 50. My friend (not/mind)……………..cooking.

câu 1 : cho CT : y-3 =x ; -2y =x ; y mũ 2 =y CT nào là H /số của x câu 2: y= 15 trên 2x-4 . tìm điều kiện của x để VP có nghĩa câu 3 cho y bằng x mũ 2 +3x + 2x . tính y (-1) ; y(0) ; y (1 phần 2 ) câu 4 cho y =f(x)= ax nhân CMR a. với x1 ; x2 bất kì ta có f (x1+x2) =f(x1) + f(x2) b. với mọi K thuộc Q LÀ (KX) = k nhân f (x)

tại sao châu mĩ có nhiều thành phần da

vẽ tranh về chủ đề an toàn giao thông nhó ! p/s: đơn giản mà vẫn đẹp thôi nhé mn, ko cần cầu kì quá đouu

29. Her appearance is ………………………… today. She shouldn’t come. (need) 30. They are living in a ………………………… decorated house. (beauty) 31. A person who is interested in conservation is a …………………………. (conserve) 32. There are a lot of technological ………………………… designed to save energy. (innovate) 33. This man …………………………in writing (success) 34. She always ………………………… listens to what she is told. (attention)

Loga.vn - Cộng Đồng Luyện Thi Trực Tuyến