Tây Ban Nha với 4 lần vô địch

` x + 1 = 0 ` 
\[ => 
x = -1
\]
\[
(-1 + 1)^2 = -1 + 1
\]
\[
0 = 0
\]
Vậy \( x = -1 \) là một nghiệm của phương trình.
\[
\frac{(x + 1)^2}{x + 1} = \frac{x + 1}{x + 1}
\]
\[
x + 1 = 1
\]
\[
x = 0
\]

a) n = 1 là giá trị duy nhất sao cho 7n là số nguyên tố ( vì 7 . 1 = 7, và 7 là số nguyên tố) 

b) Không tồn tại giá trị n nào để ` 3^n ` + 18 là số nguyên tố khi 7n cũng là số nguyên tố

23. Peter could skate when he was 12.

24. They have not visited Europe for two years.

25. Humans are more intelligent than robots.

 Bài 1: 

A) \((a - 3)^2 - 4\)
\[
(a - 3)^2 - 4 = [(a - 3) - 2][(a - 3) + 2]
\]
\[
= (a - 5)(a - 1)
\]

B) \((a - 2b)^2 - b^2\)
\[
(a - 2b)^2 - b^2 = [(a - 2b) - b][(a - 2b) + b]
\]
\[
= (a - 3b)(a - b)
\]

C) \((4a + 3b)^2 - (2a + b)^2\)
\[
(4a + 3b)^2 - (2a + b)^2 = [(4a + 3b) - (2a + b)][(4a + 3b) + (2a + b)]
\]
\[
= (2a + 2b)(6a + 4b) = 2(a + b) \cdot 2(3a + 2b)
\]
\[
= 2(a + b)(3a + 2b)
\]

D) \((2a - b)^2 - (a - b)^2\)
\[
(2a - b)^2 - (a - b)^2 = [(2a - b) - (a - b)][(2a - b) + (a - b)]
\]
\[
= (a)(3a - 2b)
\]
\[
= a(3a - 2b)
\]

E) \((x - y)^2 - (2x - y)^2\)
\[
(x - y)^2 - (2x - y)^2 = [(x - y) - (2x - y)][(x - y) + (2x - y)]
\]
\[
= (-x)(3x - 2y)
\]
\[
= -x(3x - 2y)
\]

 Bài 2: 

1) \(4a^2 + 12ab + 9b^2\)
\[
4a^2 + 12ab + 9b^2 = (2a + 3b)^2
\]

2) \(-4a^2 - b^2 + 4ab\)
\[
-4a^2 - b^2 + 4ab = -[(2a - b)^2]
\]
\[
= -(2a - b)(2a - b)
\]

Bài 3: 

1) \(a^3 - 27b^3\)
\[
a^3 - 27b^3 = (a - 3b)(a^2 + 3ab + 9b^2)
\]

2) \(a^3 - b^6\)
\[
a^3 - b^6 = (a - b^2)(a^2 + ab^2 + b^4)
\]

3) \(64a^3 - 27b^3\)
\[
64a^3 - 27b^3 = (4a - 3b)(16a^2 + 12ab + 9b^2)
\]

Năm học mới em có kì vọng đó là:

+ Dành nhiều thời gian hơn để học bài và làm bài tập.

+ Tập trung lắng nghe giảng bài trên lớp và tham gia thảo luận.

+ Tự học thêm tài liệu ngoài để mở rộng kiến thức.

+ Tham gia các hoạt động ngoại khoá và câu lạc bộ trong trường.

+ Tạo điều kiện để giao lưu và học hỏi từ bạn bè.

1. My grandfather is buying some fruits at the supermarket.

   (-) My grandfather is not buying any fruits at the supermarket.  
   (?) Is my grandfather buying any fruits at the supermarket?

2. Hong is studying French in the library.

   (-) Hong is not studying French in the library.  
   (?) Is Hong studying French in the library?

3. James is running in the park.

   (-) James is not running in the park.  
   (?) Is James running in the park?

4. My dog is playing in the yard now.

   (-) My dog is not playing in the yard now.  
   (?) Is my dog playing in the yard now?

5. Tom is playing games in the room.

   (-) Tom is not playing games in the room.  
   (?) Is Tom playing games in the room?

6. Their students are studying hard for the competition.

   (-) Their students are not studying hard for the competition.  
   (?) Are their students studying hard for the competition?

7. All of Jack's friends are singing and dancing at the party.

   (-) All of Jack's friends are not singing and dancing at the party.  
   (?) Are all of Jack's friends singing and dancing at the party?

8. My children are traveling around Asia now.

   (-) My children are not traveling around Asia now.  
   (?) Are my children traveling around Asia now?

9. Her little brother is drinking milk.

   (-) Her little brother is not drinking milk.  
   (?) Is her little brother drinking milk?

10. His teacher is speaking English with the foreigner.

   (-) His teacher is not speaking English with the foreigner.  
   (?) Is his teacher speaking English with the foreigner?

` A=1/(2x4) + 1/(4x6) + 1/(6x8) + ... + 1/(96x98) + 1/(98x100) `

` 2A=2/(2x4) + 2/(4x6) + 2/(6x8) + ... + 2/(96x98) + 2/(98x100) ` 

` 2A=1/2-1/4+1/4-1/6+1/6-1/8+...+1/96-1/98+1/98-1/100` 

` 2A=1/2-1/4+1/4-1/6+1/6-1/8+...+1/96-1/98+1/98-1/100 `

` 2A=1/2-1/100 ` 

` 2A=49/100 ` 

` =>A=49/100:2 ` 

` =>A=49/200 `

\[
(5\sqrt{5} - 2\sqrt{3} - 2\sqrt{5})(3\sqrt{5} - \sqrt{3} + 3\sqrt{3})
\]

\[
(3\sqrt{5} - 2\sqrt{3})(3\sqrt{5} - \sqrt{3} + 3\sqrt{3})
\]

\[
(3\sqrt{5} - 2\sqrt{3})(3\sqrt{5} + 2\sqrt{3})
\]
\[
(a - b)(a + b) = a^2 - b^2
\]
\[
= (3\sqrt{5})^2 - (2\sqrt{3})^2
\]
\[
= 9 \cdot 5 - 4 \cdot 3
\]
\[
= 45 - 12
\]
\[
= 33
\]

1.  to her son

2. for Pedro

3. to charity

4. for Laura

5. to poor children

6. to Marcos

7.. to my boyfriend

8.  to his wife

9. for me

10. to the company

11. an email

12. with your housework

13. a bag full of money

14. on the French revolution

15. your help