1.

2.Second

3.Date

3.First

1 february

eyes

shoulders

feet

stomach

neck

1eyes

2shoulders

3feet

4stomach

5neck

1.eyes

2.shoulders

3.feet

4.stomach

5.neck

unit 1 nhé

mik nói cho bn bít dài thế sao ghi hết đc.

Bn tra lên google sẽ có đáp án đúng nhất luôn nhé.

chúc bn học tốt

Example:

1. Yes

2. Yes

3. No

4. Yes

5. No

6. No

7. Yes

8. Yes

a, (Làm theo nhóm. Lần lượt phỏng vấn các bạn khác. Sử dụng các câu hỏi trên.)

b, (Nói trước lớp. Họ có phải là bạn học tốt không? Nói cho lớp nghe về điều đó.)

1. fridge

2. saucepan

Câu ba mk nghĩ chưa ra

Để mk nghĩ tiếp mk cho vô liền

1. fridge

2. 

3. oven

2. saucepan

Câu hỏi của Nguyễn Bá Huy h - Toán lớp 7 - Học toán với OnlineMath

Em tham khảo nhé!

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

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

\(\Rightarrow f\left(1\right)=\frac{1}{1^2}-\frac{1}{2^2}\)

\(f\left(2\right)=\frac{1}{2^2}-\frac{1}{3^2}\)

\(f\left(3\right)=\frac{1}{3^2}-\frac{1}{4^2}\)

...

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

Lúc đó: \(f\left(1\right)+f\left(2\right)+f\left(3\right)+...+f\left(x\right)=\frac{1}{1^2}-\frac{1}{2^2}+\frac{1}{2^2}-\frac{1}{3^2}+\frac{1}{3^2}\)

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

Thay về đầu bài, ta được: \(1-\frac{1}{\left(x+1\right)^2}=\frac{2y\left(x+1\right)^3-1}{\left(x+1\right)^2}-19+x\)

\(\Leftrightarrow1-\frac{1}{\left(x+1\right)^2}=2y\left(x+1\right)-\frac{1}{\left(x+1\right)^2}-19+x\)

\(\Leftrightarrow2y\left(x+1\right)+\left(x+1\right)=21\)

\(\Leftrightarrow\left(x+1\right)\left(2y+1\right)=21\)

\(\Rightarrow\hept{\begin{cases}x+1\\2y+1\end{cases}}\inƯ\left(21\right)=\left\{\pm1;\pm3;\pm7;\pm21\right\}\)

Lập bảng:

Mà \(x\ne0\)nên \(\left(x,y\right)\in\left\{\left(2,3\right);\left(6,1\right);\left(20,0\right);\left(-2,-11\right);\left(-4,-4\right);\left(-8,-2\right)\right\}\)\(\left(-22,-1\right)\)

I was born and grown up on the poor land in Duc Tho district, Ha Tinh province. That’s where deeply attaches to me 24 years of life. If anyone who asks me that “What’s the thing your most proud of?” .I will answer that’s my hometown. Duc Tho is the land poor where the people live by rice cultivation, breeding, and fishing. Although the life is very difficult, but the people is very friendly, and studious. In Duc Tho, there is a Tung Anh village where called “Doctor village”. Duc Tho is also the home of Tran Phu Secretary General, and marked many memories of the great leader Ho Chi Minh.
If you come to Duc Tho, you will feel many interesting things, visiting Tran Phu tombstone, La Giang dyke, rowing on La driver, and enjoying the traditional songs. In the evening, they can enjoy a special food which is “mussel rice” – just only eat one time, you will never forget.
Beautiful and unobtrusive! Duc Tho always tries to grow, and to improve the life of people, but keeping the traditional culture.

ko chép mạng và dịch cho mình luôn nha !

Ta co:   B= 1 + 3 +3² + 3³ + ....... + 3⁹⁹

                  = (1 + 3) + 3²(1+3) + 3⁴(1 + 3) + ......... + 3⁹⁸(1+3) 

               = (1 + 3)(1 + 3² +3⁴ + ......... + 3⁹⁸)

               = 4(1 + 3² +3⁴ + ........... + 3⁹⁸) \(⋮\)4 

    Vay B \(⋮\)4 

   k cho mk nha

B=(1+3)+(3²+3³)+...+(3⁹⁸+3⁹⁹)

  =(1+3)+3²(1+3)+...+3⁹⁸(1+3)

  =4+3².4+.....+3⁹⁸.4

  =4.(1+3²+...+3⁹⁸)

vì 4 chia hết cho 4 => 4.(1+3²+...+3⁹⁸) chia hết cho 4 => B chia hết cho 4 (điều phải chứng minh)

Ta có: B= (1+3)+ (3²+3³)+(3⁴+3⁵) +.....+ (3⁹⁸+3⁹⁹)

               = 4+ 3²(3+9)+3⁴(3+9)+.....+ 3⁹⁸(3+9)             

                 = 4 + 3².12+3⁴.12+....+ 3⁹⁸.12 chia hết cho 4

Vậy B chia hết cho 4

Mik nghĩ là làm như thế

Hihi