số học sinh xếp loại văn hóa giỏi là

     50:10x3=15(h/sinh)

số học sinh còn lại là

    50-15=35(h/sinh)

số học sinh loại khá là

    35:8x3=

để tui trả lời cho vài câu

Câu 1: Các quốc gia cổ đại Phương Đông ra đời : Từ cuối thiên niên kỉ IV đến đầu thiên niên kỉ III TCN .Còn các quốc gia cổ đại phương Tây ra đời: Từ đầu thiên niên kỉ I TCN .

Câu 6  : Nhà nước Văn Lang ra đời trong hoàn cảnh : Việc mở rộng nghề nông trồng lúa nước ở vùng  đồng bằng ven các con sông lớn gặp nhiều khó khăn .

 ( Nêu nhận xét )

Vì vậy,cần phải có ng chỉ huy đứng ra tập hợp  nhân dân các làng bảng chống lại lụt lội , bảo vệ mùa màng 

Câu 3; tại vì xã hội nguyên thủy phân biệt giàu nghèo ok

Bài 2:

a: \(x-\dfrac{1}{2}=\dfrac{7}{13}\cdot\dfrac{13}{28}\)

=>\(x-\dfrac{1}{2}=\dfrac{7}{28}=\dfrac{1}{4}\)

=>\(x=\dfrac{1}{4}+\dfrac{1}{2}=\dfrac{3}{4}\)

b: \(\dfrac{x}{15}=\dfrac{-3}{11}\cdot\dfrac{77}{36}\)

=>\(\dfrac{x}{15}=\dfrac{-3}{36}\cdot\dfrac{77}{11}=7\cdot\dfrac{-1}{12}=-\dfrac{7}{12}\)

=>\(x=-\dfrac{7}{12}\cdot15=-\dfrac{105}{12}=-\dfrac{35}{4}\)

c: \(x:\dfrac{15}{11}=\dfrac{-3}{12}:8\)

=>\(x:\dfrac{15}{11}=-\dfrac{1}{4}:8=-\dfrac{1}{32}\)

=>\(x=-\dfrac{1}{32}\cdot\dfrac{15}{11}=\dfrac{-15}{352}\)

Bài 1:

a: \(\dfrac{-12}{25}\cdot\dfrac{10}{9}=\dfrac{-12}{9}\cdot\dfrac{10}{25}=\dfrac{-4}{3}\cdot\dfrac{2}{5}=\dfrac{-8}{15}\)

b: \(\dfrac{10}{21}-\dfrac{3}{8}\cdot\dfrac{4}{5}\)

\(=\dfrac{10}{21}-\dfrac{12}{40}\)

\(=\dfrac{10}{21}-\dfrac{3}{10}=\dfrac{100-63}{210}=\dfrac{37}{210}\)

c: \(\dfrac{28}{11}:\dfrac{21}{22}\cdot9=\dfrac{28}{11}\cdot\dfrac{22}{21}\cdot9\)

\(=\dfrac{28}{21}\cdot\dfrac{22}{11}\cdot9=\dfrac{4}{3}\cdot2\cdot9=\dfrac{4}{3}\cdot18=24\)

d: \(-\dfrac{10}{21}\cdot\left[\dfrac{9}{15}+\left(\dfrac{3}{5}\right)^2\right]\)

\(=\dfrac{-10}{21}\cdot\left[\dfrac{3}{5}+\dfrac{9}{25}\right]\)

\(=\dfrac{-10}{21}\cdot\dfrac{15+9}{25}\)

\(=\dfrac{-10}{25}\cdot\dfrac{24}{21}=\dfrac{-2}{5}\cdot\dfrac{8}{7}=\dfrac{-16}{35}\)

e: \(\left(\dfrac{2}{3}-\dfrac{1}{2}-\dfrac{1}{3}\right)\cdot\left(1-\dfrac{1}{4}-\dfrac{1}{7}\right)\)

\(=\left(\dfrac{1}{3}-\dfrac{1}{2}\right)\cdot\dfrac{28-7-4}{28}\)

\(=\dfrac{-1}{6}\cdot\dfrac{17}{28}=\dfrac{-17}{168}\)

f: \(\left(\dfrac{15}{21}:\dfrac{5}{7}\right):\left(\dfrac{6}{5}:2\right)\)

\(=\left(\dfrac{5}{7}\cdot\dfrac{7}{5}\right):\left(\dfrac{6}{5\cdot2}\right)\)

\(=1:\dfrac{6}{10}=\dfrac{10}{6}=\dfrac{5}{3}\)

uhm.cũng đc

k mk

nhé

thank

k mình rồi mình kết bạn với cậu

- Động từ "tobe" (am, is, are, was, were) được sử dụng để diễn tả trạng thái, tính chất, hoặc vị trí của một người hoặc vật. Nó thường được sử dụng trong các trường hợp sau: 1. Diễn tả trạng thái hiện tại: I am happy. (Tôi đang hạnh phúc.)

2. Diễn tả tính chất: She is intelligent. (Cô ấy thông minh.)

3. Diễn tả vị trí: The book is on the table. (Cuốn sách đang ở trên bàn.)

- Động từ thường (regular verbs) được sử dụng trong các trường hợp khác như diễn tả hành động, sự thay đổi, hoặc sự sở hữu.

Ví dụ:

1. Diễn tả hành động: I eat breakfast every morning. (Tôi ăn sáng mỗi buổi sáng.)

2. Diễn tả sự thay đổi: The weather is getting colder. (Thời tiết đang trở nên lạnh hơn.) 3. Diễn tả sự sở hữu: This is my car. (Đây là xe của tôi.)

dùng tobe khi sau nó có tính từ , dùng động từ thường khi có thứ j đó liên quuan đến hoạt động

Ta có: \(A=\dfrac{1}{6}+\dfrac{1}{10}+\dfrac{1}{15}+...+\dfrac{1}{55}+\dfrac{1}{66}\)

\(=2\left(\dfrac{1}{12}+\dfrac{1}{20}+\dfrac{1}{30}+...+\dfrac{1}{110}+\dfrac{1}{132}\right)\)

\(=2\left(\dfrac{1}{3}-\dfrac{1}{4}+\dfrac{1}{4}-\dfrac{1}{5}+\dfrac{1}{5}-\dfrac{1}{6}+...+\dfrac{1}{10}-\dfrac{1}{11}+\dfrac{1}{11}-\dfrac{1}{12}\right)\)

\(=2\left(\dfrac{1}{3}-\dfrac{1}{12}\right)\)

\(=2\left(\dfrac{4}{12}-\dfrac{1}{12}\right)\)

\(=2\cdot\dfrac{1}{4}=\dfrac{1}{2}\)

huhu giúp mình đi mn ơi T-T

16: B

17: C

18: A

19: C

20: A

Cho mình hết bài đó đi

16: B

17: C

18: A

19: C

20: A

I really want to tell you about my friend, one of my best friend is Tuan. We were classmate during our five years at Da Nang University of Technology. He was a good student of my class. He has black hair and bright eyes and is very good – looking. Tuan and I had many things in common, especially, our hobbies. We both like traveling, billiard, table tennis, reading book and singing.

He has a kind heart and is easy to get on with everybody. The deeper our mutual understanding becomes the more we feel closely attached to each other. We are the best pupils in our class. Tuan is always at the top. He is good at every subject, but he never shows pride in his abilities and always tries to learn harder.

Tuan’s family is not rich. His parents are farmers. He often spends most of his free time doing useful things to help his parents. I like Tuan very much because of his honesty and straight forwardness. He is always ready to help his weak friends in their study; as a result, lots of friends, thanks to his whole-hearted help, have become good ones.

Among my friends, I cherish the most is Hong. She is a good student of my class, she lived with her mother in a small house near my house. She has short black hair, oval face and brown eyes. What particularly struck me about her was the smile. She looks so lovely when he smiles. She is a form of friends that I can share everything. She always believed and helped me in every situation. She is gentle and endearing all friends. She likes Literacy, reading, listening to music and go under heaven mua. Hong and I have a lot in common with each other, has become good friends over the past 5 years. Although time has passed long in any case, Hong and I also trying to keep this friendship.

This writing is about my best friend, Son

We go to the same school and we are been together for five years. Son is very friendly. He has short black hair and a round face. He is clever and kind but he isn't boring. He always help people. His favourite subject is Math and English. He often plays football and reads a story. Every morning, he and me ride our bike to school. After finish at school, he and me ride our bike to come back home. He is funny. So, he always make me smile. I learn lots of from his very much. Son and me are good friend forever.