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24 tháng 10 2021

\(1,=\left(x-3\right)^2\\ 2,=\left(5+x\right)^2\\ 3,=\left(\dfrac{1}{2}x+2b\right)^2\\ 4,=\left(\dfrac{1}{3}-y^4\right)^2\\ 5,=\left(x+2y\right)\left(x^2-2xy+4y^2\right)\\ 6,=\left(2y-5\right)\left(4y^2+10y+25\right)\\ 7,=\left(a^2-b\right)\left(a^4+a^2b+b^2\right)\\ 8,=\left(x-5\right)^2\\ 9,=8\left(x^3-\dfrac{1}{64}\right)=8\left(x-\dfrac{1}{4}\right)\left(x^2+\dfrac{1}{4}x+\dfrac{1}{16}\right)\)

24 tháng 10 2021

Bn dùng hằng đẳng thức đáng nhớ nhé.

Thêm một chút kiên thức về bài:

\(\left(\dfrac{a}{b}\right)^2=\dfrac{a^2}{b^2}\)

\(a^{xy}=\left(a^x\right)^y\)

23 tháng 12 2021

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

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

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

23 tháng 12 2021

\(e,=\dfrac{1}{x-1}-\dfrac{2x}{\left(x^2+1\right)\left(x-1\right)}=\dfrac{x^2-2x+1}{\left(x^2+1\right)\left(x-1\right)}=\dfrac{\left(x-1\right)^2}{\left(x^2+1\right)\left(x-1\right)}=\dfrac{x-1}{x^2+1}\\ f,=\dfrac{3x-1}{2\left(3x+1\right)}+\dfrac{3x+1}{2\left(3x-1\right)}-\dfrac{6x}{\left(3x-1\right)\left(3x+1\right)}\\ =\dfrac{9x^2-6x+1+9x^2+6x+1-12x}{2\left(3x-1\right)\left(3x+1\right)}=\dfrac{2\left(3x-1\right)^2}{2\left(3x-1\right)\left(3x+1\right)}=\dfrac{3x-1}{3x+1}\)

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

mng giúp em đi ạ em cần rất gấp đấy ạ 11. If you knew Japanese, you would understand what I mean.→ Were ............................................................12. If I were a bird, I would fly.→ Were ............................................................13. If you had trained harder, you would have won the game.→ Had ............................................................14. If I were you, I would not behave in such a polite manner in front of my boss.→ Were...
Đọc tiếp

mng giúp em đi ạ em cần rất gấp đấy ạ 

11. If you knew Japanese, you would understand what I mean.

→ Were ............................................................

12. If I were a bird, I would fly.

→ Were ............................................................

13. If you had trained harder, you would have won the game.

→ Had ............................................................

14. If I were you, I would not behave in such a polite manner in front of my boss.

→ Were ............................................................

15. If I studied at a prestigious university, I would have the opportunity to work abroad.

→ Were ............................................................

16. If he has a temperature, he will see the doctor.

→ Should............................................................

17. If my friends come, I will be very happy.

→ Should............................................................

18. If she had earned a lot of money, she would have flown to New York.

→ Had ............................................................

19. If I knew your father, I would tell him to help you practice harder.

→ Were............................................................

20. If she needs some more money, she can take an extra 200.

→ Should............................................................

1
3 tháng 10 2021

11. If you knew Japanese, you would understand what I mean.

→ Were ........you to know Japanese, you would understand what I mean.....................................................

12. If I were a bird, I would fly.

→ Were ..........I a bird, I would fly. ..................................................

13. If you had trained harder, you would have won the game.

→ Had ....you trained harder, you would have won the game.........................................................

14. If I were you, I would not behave in such a polite manner in front of my boss.

→ Were .......I you, I would not behave in such a polite manner in front of my boss......................................................

15. If I studied at a prestigious university, I would have the opportunity to work abroad.

→ Were ........I to study at a prestigious university, I would have the opportunity to work abroad. ....................................................

16. If he has a temperature, he will see the doctor.

→ Should..........he have a temperature, he will see the doctor...................................................

17. If my friends come, I will be very happy.

→ Should.........my friend come, I will be very happy....................................................

18. If she had earned a lot of money, she would have flown to New York.

→ Had .....she earned a lot of money, she would have flown to New York.......................................................

19. If I knew your father, I would tell him to help you practice harder.

→ Were............I to know your father, I would tell him to help you practice harder.................................................

20. If she needs some more money, she can take an extra 200.

→ Should.......she need some more money, she can take an extra 200.....................................................

8 tháng 11 2021

Bài 1:

\(a,\dfrac{25}{14x^2y}=\dfrac{75y^4}{42x^2y^5};\dfrac{14}{21xy^5}=\dfrac{28x}{42x^2y^5}\\ b,\dfrac{3x+1}{12xy^4}=\dfrac{3x\left(3x+1\right)}{36x^2y^4};\dfrac{y-2}{9x^2y^3}=\dfrac{4y\left(y-2\right)}{36x^2y^4}\\ c,\dfrac{1}{6x^3y^2}=\dfrac{6y^2}{36x^3y^4};\dfrac{x+1}{9x^2y^4}=\dfrac{4x\left(x+1\right)}{36x^3y^4};\dfrac{x-1}{4xy^3}=\dfrac{9x^2y\left(x-1\right)}{36x^3y^4}\\ d,\dfrac{3+2x}{10x^4y}=\dfrac{12y^4\left(3+2x\right)}{120x^4y^5};\dfrac{5}{8x^2y^2}=\dfrac{75x^2y^3}{120x^4y^5};\dfrac{2}{3xy^5}=\dfrac{80x^3}{120x^4y^5}\)

22 tháng 10 2021

1: \(\left(x+2y\right)^2=x^2+4xy+4y^2\)

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

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

22 tháng 10 2021

Áp dụng hằng đẳng thức đáng nhớ:

1. (a + b)2 = a2 + 2ab + b2 

2. (a - b)2 = a2 - 2ab + b2

3. a2 - b2 = (a + b)(a - b)

4. (a + b)3 = a3 + 3a2b + 3ab2 + b3

5. (a - b)3 = a3 - 3a2b + 3ab2 - b3

6. a3 + b3 = (a + b)(a2 - ab + b2)

7. a3 - b3 = (a - b)(a2 + ab + b2)

21 tháng 9 2021

Biết mỗi câu 1 thôi :v  : Trích trong vb Mẹ tôi của Ét-môn-đô-đơ A-mi-xi

 

21 tháng 9 2021

1. Mẹ tôi - Edmondos De Amicis.

2. Từ liên kết: Bố.

3. Có thể hi sinh tất cả vì con mình, yêu con da diết, ...

4. Em sẽ xin lỗi mẹ và cầu mong mẹ sẽ tha lỗi cho mình.

Cho cả năm luôn này cj:) Ngữ pháp tiếng Anh lớp 8 cả năm - Hiến thức tiếng Anh lớp 8 học kì 1 + học kì 2 - VnDoc.com

12 tháng 1 2022

:V

15 tháng 2 2020

Ta có: \(\frac{x+2}{y+10}\)\(=\)\(\frac{1}{5}\)\(\Rightarrow\)\(5\left(x+2\right)=y+10\)(1)

             \(y-3x=2\)\(\Rightarrow\)\(y+2=3x\)                              (2)

Thay (2) vào (1) ta có:

\(5\left(x+2\right)=\left(y+2\right)+8\)

\(5x+10=3x+8\)

\(5x-3x=8-10\)

\(2x=-2\)

\(x=-2:2\)

\(x=-1\)

Vậy: x=-1

Chúc bạn làm bài tốt!

Bài 5: 

d: Áp dụng tính chất của dãy tỉ số bằng nhau, ta được:

\(\dfrac{x}{2}=\dfrac{y}{3}=\dfrac{z}{4}=\dfrac{x+y-z}{2+3-4}=\dfrac{-20}{1}=-20\)

Do đó: x=-40; y=-60; z=-80