Long Quân, một vị vua tài ba và tinh thông võ nghệ, đã có một hành động đầy tinh thần hiệp sĩ. Trong thời gian Lam Sơn kháng chiến, khi quân Lam Sơn còn thiếu vũ khí, Long Quân đã tự mình mang gươm thần của mình đến trao cho nghĩa quân. Hành động này không chỉ thể hiện lòng yêu nước và tình đồng đội mà còn khẳng định ý chí chiến đấu vô cùng kiên cường của ông. Gươm thần của Long Quân đã trở thành biểu tượng của sự quyết tâm và sức mạnh của quân Lam Sơn trong cuộc kháng chiến chống lại thực dân. Đây là một truyền thống tốt đẹp và một nguồn cảm hứng vô cùng lớn cho các thế hệ sau này.

a, \(\left\{{}\begin{matrix}35x-28y=21\\35x-45y=40\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}17y=-19\\x=\dfrac{3+4y}{5}\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}y=-\dfrac{19}{17}\\x=-\dfrac{13}{17}\end{matrix}\right.\)

b, Đặt x;y khác 0 

Đặt 1/x = t ; 1/y = u 

\(\left\{{}\begin{matrix}t-8u=18\\5t+4u=51\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}5t-40u=90\\5t+4u=51\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}-44u=39\\t=18+8u\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}u=-\dfrac{39}{44}\\t=\dfrac{120}{11}\end{matrix}\right.\)

Theo cách đặt y = -44/39 ; x = 11/120 (tm)

\(a,\\ \Leftrightarrow\left\{{}\begin{matrix}35x-28y=21_{\left(1\right)}\\35x-45y=40_{\left(2\right)}\end{matrix}\right.\\ Lấy\left(1\right)-\left(2\right),ta.đc:\\ -17y=19\Leftrightarrow y=\dfrac{-19}{17}\\ Thay.vào.\left(1\right):\\ 35x-28.\dfrac{-19}{17}=21\Leftrightarrow x=\dfrac{-5}{17}\) 

Vậy ......

\(b,\\ \Leftrightarrow\left\{{}\begin{matrix}\dfrac{1}{x}=18+\dfrac{1}{y}\\5.\left(18+\dfrac{1}{y}\right)+\dfrac{4}{y}=51\end{matrix}\right.\\ \Leftrightarrow\left\{{}\begin{matrix}\dfrac{1}{x}=18+\dfrac{1}{y}\\\dfrac{9}{y}=-39\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}\dfrac{1}{x}=18-\dfrac{13}{3}\\\dfrac{1}{y}=\dfrac{-13}{3}\end{matrix}\right.\\ \Leftrightarrow\left\{{}\begin{matrix}\dfrac{1}{x}=\dfrac{41}{3}\\\dfrac{1}{y}=\dfrac{-13}{3}\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=\dfrac{3}{41}\\y=\dfrac{-3}{13}\end{matrix}\right.\)

- Bài này phải có điều kiện \(x>0\) thì mới làm được nhé bạn.

\(P=\dfrac{x^3+2021}{x}=x^2+\dfrac{2021}{x}=x^2+\dfrac{2021}{2x}+\dfrac{2021}{2x}\)

Áp dụng bất đẳng thức Cauchy cho 3 số dương ta có:

\(x^2+\dfrac{2021}{2x}+\dfrac{2021}{2x}\ge3\sqrt[3]{x^2.\dfrac{2021}{2x}.\dfrac{2021}{2x}}=3\sqrt[3]{\dfrac{2021^2}{4}}\)

Dấu "=" xảy ra khi \(x^2=\dfrac{2021}{2x}\Leftrightarrow x=\sqrt[3]{\dfrac{2021}{2}}\)

Vậy \(MinP=3\sqrt[3]{\dfrac{2021^2}{4}}\)

1.

a) Mary is as thin as her brother.

b) A lemon is not as sweet as an orange.

c) A donkey cannot run as quick as a horse.

d) This dress is twice as pretty as that one.

e)They don't drive a car as dangerous as us.

1. So sánh ngang bằng.

a. Mary/thin/her brother.

Mary is as thin as her brother.

b. A lemon/not sweet/ an orange. 

A lemon isn't as sweet as an orange.

c. A donkey/not run/quick/ a horse.

A donkey doesn't run as quickly as a horse.

d. This dress/twice/pretty/that one.

This dress is twice as pretty as that one.

e. They/ drive a car/ dangerous/ we.         

They drive a car as dangerously as we do.

2. So sánh hơn: (Nhấn mạnh các câu ss hơn)

a. this film /popular/ that one.       

This film is much more popular than that one.

b. A bird/can fly/slow/ a plane.

A bird can fly much more slowly than a plane.

c. Ba/ friendly/ Nam.

Ba is much more friendly than Nam.

d .Your house/far/from school /my house.

Your house is much farther from school than my house.

e. My father / drive/ careful/ I

My father drives much more carefully than I do.

3. So sánh nhất: (Nhấn mạnh theo 2 cách đã học)

a. This road/short /way/ in the city.

This road is by far the shortest way in the city.

b. Lan/ walk/ slow / in my class.

Lan walks by far the most slowly in my class.

c. Indian tea/bad/ of all.

Indian tea is by far the worst of all.

d. Anna/ work/ simple/girl/ in the world.

Anna works by far the simplest girl in the world.

e. Jack/ can tell/ the stories/ humourous/ in the world.

Jack can tell the stories by far the most humorously in the world.

II. Rewrite these sentences

1.      This street is narrower than that one

Þ    That street isn't as wide as this one.

Þ    That street is wider than this one.

2. Linda drives more carefully than Peter

Þ    Peter doesn't drive as carefully as Linda.

Þ    Peter drives more carelessly than Linda.

3.Your car is more convenient than mine

Þ    My car isn't as convenient as yours.

Þ    My car is less convenient than yours.

4. We behave more politely than her

Þ    She doesn't behave as politely as us.

Þ    She behaves more impolitely than us.

5.I  cook better than my mother

Þ    my mother doesn't cook as well as me.

Þ    my mother cooks worse than me.

6. Anna isn’t as confident as me

=> I am more confident than Anna.

7. This book isn’t as boring as that one

Þ    That book is more boring than this one.

8. I don’t work as effectively as he does

=> He works more effectively than I do.

9. My bedroom isn’t so comfortable as yours

Þ    Your bedroom is more comfortable than mine.

10. John didn’t speak English as well as Mary

=> Mary spoke English better than John.

11. Peter can dance the most gracefully in my city

=> No one in my city can dance as gracefully as Peter.

=> No one in my city can dance more gracefully than Peter.

12. Kangaroo is the most unique animal in the world

=> No animal in the world is as unique as kangaroo.

=> No animal in the world is more unique than kangaroo.

13. No river in the world is longer than Nile

=> Nile is the longest river in the world.

14. No student in my class learns Maths more intelligently than John

=> John learns Maths the most intelligently in my class.

15. If you read many books, you will have much knowledge

→ The more books you read, the more knowledge you will have.

16. He speaks too much and people feel bored.

→ The more he speaks, the more bored people feel.

2. 

a) This film is more popular than that one.

b) A bird can fly slower that a plane.

c) Ba is more friendly than Nam.

d) Your house is farther from school than my house.

e) My father drives more careful than I.

Câu 13: 

Ta có: \(f\left(x\right)>0\Leftrightarrow3x-m>0\Leftrightarrow3x>m\)

Mà x>1 hay 3x>3

Vậy \(m\le3\)

Đáp án C

Câu 14:

(d): x-2y+1=0 hay \(\dfrac{1}{2}x+\dfrac{1}{2}=y\)

Gọi phương trình đường thẳng cần tìm là: y=ax+b

Phương trình cần tìm đi qua A nên ta có: 2=-2a+b

Để phương trình cần tìm vuông góc với (d) thì: \(a.\dfrac{1}{2}=-1\Rightarrow a=-2\)\(\Rightarrow b=-2\)

Vậy phương trình cần tìm là: \(y=-2x-2\)

Đáp án C

Travelling by train is slower but more interesting than travelling by plane.

My brother worked as an engineer for a printing factory last year.

Travelling by train is slower but more interesting than travelling by plane

My brother worked as an engineer in the printing factory last year