1) \(\left(2x+3\right)^2=4x^2+12x+9\)

\(\left(3x+2\right)^2=9x^2+12x+4\)

\(\left(2x+5\right)^2=4x^2+20x+25\)

\(\left(2x+\dfrac{1}{3}\right)^2=4x^2+\dfrac{4}{3}x+\dfrac{1}{9}\)

\(\left(3x+\dfrac{1}{3}\right)^2=9x^2+2x+\dfrac{1}{9}\)

2)  \(\left(2x-3\right)^2=4x^2-12x+9\)

\(\left(3x-2\right)^2=9x^2-12x+4\)

\(\left(2x-5\right)^2=4x^2-20x+25\)

\(\left(2x-\dfrac{1}{3}\right)^2=4x^2-\dfrac{4}{3}x+\dfrac{1}{9}\)

\(\left(3x-\dfrac{1}{3}\right)^2=9x^2-2x+\dfrac{1}{9}\)

3) \(\left(2x-3\right)\left(2x+3\right)=4x^2-9\)

\(\left(3x-4\right)\left(3x+4\right)=9x^2-16\)

\(\left(2x-5\right)\left(2x+5\right)=4x^2-25\)

\(\left(x-\dfrac{1}{2}\right)\left(x+\dfrac{1}{2}\right)=x^2-\dfrac{1}{4}\)

\(\left(2x-\dfrac{1}{3}\right)\left(2x+\dfrac{1}{3}\right)=4x^2-\dfrac{1}{9}\)

1: \(\left(2x+3\right)^2=4x^2+12x+9\)

\(\left(3x+2\right)^2=9x^2+12x+4\)

\(\left(2x+5\right)^2=4x^2+20x+25\)

\(\left(2x+\dfrac{1}{3}\right)^2=4x^2+\dfrac{4}{3}x+\dfrac{1}{9}\)

\(\left(3x+\dfrac{1}{3}\right)^2=9x^2+2x+\dfrac{1}{9}\)

54/31 : 12/64 - 8 = 40/31

k nhé:))

\(=\frac{40}{31}\)

\(\frac{54}{31}\div\frac{12}{64}-8\)

\(=\frac{54}{31}\div\frac{3}{16}-8\)

\(=\frac{288}{31}-\frac{8}{1}\)

\(=\frac{288}{31}-\frac{248}{31}\)

\(=\frac{40}{31}\)

HT

3.20:

a) (-28) + (-35) – 92 + (-82)

= -28 – 35 – 92 – 82 

= - (28 + 35 + 92 + 82)

= - [(28 + 82) + (35 + 92)]

= - (110 + 127)

= - 237.

b) 15 – (-38) + (-55) – (+47)

= 15 + 38 – 55 – 47

= 53 – 55 – 47

= - (55 – 53) – 47

= - 2 – 47

= - (2 + 47)

= - 49

3.21:

a) (62 - 81) – (12 – 59 + 9)

= 62 – 81 – 12 + 59 – 9

= (62 – 12) – (81 + 9) + 59

= 50 – 90 + 59

= - (90 – 50) + 59

= - 40 + 59

= 59 – 40

= 19

b) 39 + (13 – 26) – (62 + 39)

= 39 + 13 – 26 – 62 – 39

= (39 – 39) – (26 + 62) + 13

= 0 – 88 + 13

= - 88 + 13

= - (88 – 13)

= - 75.

3.22

a) 32 – 34 + 36 – 38 + 40 – 42

= (32 – 34) + (36 – 38) + (40 – 42)

= - (34 – 32) – (38 – 36) – (42 – 40)

= - 2 – 2 – 2

= - (2 + 2 + 2)

= - 6.

b) 92 – (55 – 8) + (-45)

= 92 – 55 + 8 – 45

= (92 + 8) – (55 + 45)

= 100 – 100 

= 0

3.23

a) 386 – (287 + 386) – (13 + 0) 

= 386 – 287 – 386 – 13

= (386 – 386) – (287 + 13)

= 0 – 300

= - 300

b) 332 – (681 + 232 – 431)

= 332 – 681 – 232 + 431

= (332 – 232) – (681 – 431)

= 100 – 250

= - (250 – 100)

= - 150.

Kh0nq chấp nhận nka :<

10. ……………. festival do you choose? - I choose Elephant Race Festival.

A. What B. How C. Which D. When

11. ……………. often is Burning Festival held? - It's held every year.

A. Which B. When C. What D. How

12. ……………. does the teacher say La Tomatina sounds unusual? - Because people throw tomatoes at each other for one hour at the festival.

A. What B. When C. Why D. How

13. He ___________ books for poor children for years.

A. has collected B. collects C. is collecting D. collected

14. Next Saturday at this time, we _____ on the beach in Mexico.

A. will relax B. will be relaxing C. has relaxed D. relax

15. Anne and Joe _____ by sea tomorrow

A. travel B. will travel C. travels D. travelled

16. I_____ in Jakarta, but now I live in New York. [use to + V-inf]

A. used to living B. used to living C. used to live D. am used to live

17. Jane_____ for the telephone company, but now she has a job at the post office.

A. used to working B. used to worked C. is used to work D. used to work

18. …………. he spent much money on the film, it wasn't a big success.

A. Even B. But C. Although D. Despite

19. We didn't find it funny………..it was a comedy.

A. in spite of B. despite C. although D. but

20. I went to the cinema with my friends yesterday ………… feeling very tired.

A. although B. in spite C. despite D. but

21. Let's go to the Victor Cinema. I'm sure you'll find the film…………

A. excites B. excite C. excited D. exciting

22. I was ……… to learn that the director of that gripping film has won the first prize.

A. interest B. interests C. interested D. interesting

23. The film was boring, ____ we went home.

A. so B. when C. but D. if

24. Nam was absent from class yesterday ____ he felt sick.

A. so B. because C. although D. but

25. These books aren’t yours, ____________?

A.are these B. aren’t these C. are they D. aren’t they

26. No one died in the accident, ______________?

A.did they B. didn’t they C. did he D. didn’t he

27. Tom knows Alice, _____________?

A.doesn’t he B. is he C. does he D. isn’t he

28. Peter never comes to class late, ________________?

A. doesn’t he B. doesn’t Peter C. does he D. does Peter

29. ……… computer is a laptop, but ……… is a desktop.

A. Hers - you B. Her - your C. My - yours D. Mine - yours

30. We gave them ……… ID number, and they gave us ……….

A. ours - theirs B. our - theirs C. our -their D. ours - their

Mn giúp mik ak câu nào mn bt thì lm còn lm hết đc thì càng tốt nhé TKS

10. ……………. festival do you choose? - I choose Elephant Race Festival.

A. What B. How C. Which D. When

11. ……………. often is Burning Festival held? - It's held every year.

A. Which B. When C. What D. How

12. ……………. does the teacher say La Tomatina sounds unusual? - Because people throw tomatoes at each other for one hour at the festival.

A. What B. When C. Why D. How

13. He ___________ books for poor children for years.

A. has collected B. collects C. is collecting D. collected

14. Next Saturday at this time, we _____ on the beach in Mexico.

A. will relax B. will be relaxing C. has relaxed D. relax

15. Anne and Joe _____ by sea tomorrow

A. travel B. will travel C. travels D. travelled

16. I_____ in Jakarta, but now I live in New York. [use to + V-inf]

A. used to living B. used to living C. used to live D. am used to live

17. Jane_____ for the telephone company, but now she has a job at the post office.

A. used to working B. used to worked C. is used to work D. used to work

18. …………. he spent much money on the film, it wasn't a big success.

A. Even B. But C. Although D. Despite

19. We didn't find it funny………..it was a comedy.

A. in spite of B. despite C. although D. but

20. I went to the cinema with my friends yesterday ………… feeling very tired.

A. although B. in spite C. despite D. but

21. Let's go to the Victor Cinema. I'm sure you'll find the film…………

A. excites B. excite C. excited D. exciting

22. I was ……… to learn that the director of that gripping film has won the first prize.

A. interest B. interests C. interested D. interesting

23. The film was boring, ____ we went home.

A. so B. when C. but D. if

24. Nam was absent from class yesterday ____ he felt sick.

A. so B. because C. although D. but

25. These books aren’t yours, ____________?

A.are these B. aren’t these C. are they D. aren’t they

26. No one died in the accident, ______________?

A.did they B. didn’t they C. did he D. didn’t he

27. Tom knows Alice, _____________?

A.doesn’t he B. is he C. does he D. isn’t he

28. Peter never comes to class late, ________________?

A. doesn’t he B. doesn’t Peter C. does he D. does Peter

29. ……… computer is a laptop, but ……… is a desktop.

A. Hers - you B. Her - your C. My - yours D. Mine - yours

30. We gave them ……… ID number, and they gave us ……….

A. ours - theirs B. our - theirs C. our -their D. ours - their

1. Thơ sáu chữ. 2 khổ thơ

2. Nhân hóa (thời gian chạy qua tóc mẹ). Tác dụng: khiến cho bài văn hay hơn, có cảm xúc hơn.

3. Chạy ở đây nêu lên cảm xúc buồn bã và tiếc nuối của tác giả , ý chỉ thời gian đã trôi qua rất nhanh nên mái tóc của mẹ giờ đây đã bạc màu. Từ chạy ở đây là nghĩa chuyển.

4. Hãy luôn biết ơn, hiếu thảo và yêu thương bố mẹ - người luôn cho ta những điều tốt đẹp nhất

Bạn bảo tình bạn là rất tuyệt vời

nhưng ai ngờ

tình bạn giả tạo là có thật

ko phải đâu thêm tí cho vui chưa có chuyện đó

6 + 6 + 2007 = 2019

k cho mik nha

ta có Cu ko tác dụng được vs H2SO4 

-> 2,24 lít khí H2 đc tạo ra là do phản ứng HH của Fe va H2SO4 

\(PTHH:\) \(Fe+H_2SO_4->FeSO_4+H2\)

n H2 = 2,24 :22,4=0,1 mol 

n H2 = n Fe =0,1 mol 

m Fe = 0,1.56=5,6 g 

m Cu = 10-5,6=4,4 g 

vậy giá trị của x là 4,4 g

26 

PTHH : \(Zn+2HCl->ZnCl_2+H_2\)

n Zn = 6,5:65=0,1 mol

n ZnCl2 = n Zn =0,1 mol

m ZnCl2 = 0,1.(65+35,5.2)=13,6 g

ta có Cu ko tác dụng được vs H2SO4 

-> 2,24 lít khí H2 đc tạo ra là do phản ứng HH của Fe va H2SO4 

n H2 = 2,24 :22,4=0,1 mol 

n H2 = n Fe =0,1 mol 

m Fe = 0,1.56=5,6 g 

m Cu = 10-5,6=4,4 g 

vậy giá trị của x là 4,4 g