a. x² - 2x

⇔ x(x - 2)

b. 3x - 6y

⇔ 3(x - 2y)

c. 5(x + 3y) - 15x(x + 3y)

⇔ (5 - 15x)(x + 3y)

d. 3(x - y) - 5x(y - x)

⇔ 3(x - y) + 5x(x - y)

⇔ (3 + 5x)(x - y)

2B: 

a: \(\left(x+1\right)^2-\left(x+1\right)=x\left(x+1\right)\)

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

c: \(xy\left(x-y\right)-2x+2y=\left(x-y\right)\left(xy-2\right)\)

d: \(y\left(x-y\right)^2+x\left(y-x\right)^2=\left(x-y\right)^2\cdot\left(x+y\right)\)

Kinh Dương Vương(涇陽王): 2879 - 2794 TCN (số năm trị vì là ước đoán). Huý là Lộc Tục (祿續).Hùng Hiền vương(雄賢王), còn được gọi là Lạc Long Quân (駱龍君 hoặc 雒龍君 hoặc 貉龍君): 2793 - 2525 TCN. Huý là Sùng Lãm (崇纜).Hùng Lân vương (雄麟王): 2524 - 2253 TCNHùng Việp vương (雄曄王): 2252 - 1913 TCNHùng Hi vương (雄犧王): 1912 - 1713 TCN (phần bên trái chữ "hi" 犧 là bộ "ngưu" 牛)Hùng Huy vương (雄暉王): 1712 - 1632 TCNHùng Chiêu vương (雄昭王): 1631 - 1432 TCNHùng Vĩ vương (雄暐王): 1431 - 1332 TCNHùng Định vương (雄定王): 1331 - 1252 TCNHùng Hi vương (雄曦王): 1251 - 1162 TCN (phần bên trái chữ "hi" 犧 là bộ "nhật" 日)Hùng Trinh vương (雄楨王): 1161 - 1055 TCNHùng Vũ vương (雄武王): 1054 - 969 TCNHùng Việt vương (雄越王): 968 - 854 TCNHùng Anh vương (雄英王): 853 - 755 TCNHùng Triêu vương (雄朝王): 754 - 661 TCNHùng Tạo vương (雄造王): 660 - 569 TCNHùng Nghị vương (雄毅王): 568 - 409 TCNHùng Duệ vương (雄睿王): 408 - 258 TCN

Người ta không nói rõ chỉ biết là 18 ông thì đều lấy hiệu là Hùng vương hết

ai biết

#include <bits/stdc++.h>

using namespace std;

double a,b;

int main()

{

cin>>a>>b;

cout<<(a+b)*2;

return 0;

}

Bài 1:

Vì AD là p/g góc A nên \(\widehat{A_1}=\widehat{A_2}=\dfrac{1}{2}\widehat{BAC}=30^0\)

Mà \(\widehat{A_2}+\widehat{C}+\widehat{D_1}=180^0\Rightarrow\widehat{D_1}=180^0-30^0-40^0=110^0\)

Mà AE//BC nên \(\widehat{EAD}=\widehat{D_1}=110^0\left(so.le.trong\right)\)

Vì DE//AC nên \(\widehat{A_2}=\widehat{D_2}=30^0\left(so.le.trong\right);\widehat{D_3}=\widehat{C}=40^0\left(đồng.vị\right)\)

Vì AE//BC nên \(\widehat{D_3}=\widehat{E}=40^0\)

Vậy các góc tg ADE là \(\widehat{A}=110^0;\widehat{D}=30^0;\widehat{E}=40^0\)

Bài 2:

a, Xét tg ABH và tg DBH có 

\(\left\{{}\begin{matrix}\widehat{BAH}=\widehat{BDH}=90^0\\\widehat{ABH}=\widehat{DBH}\left(BH.là.p/g\right)\\BH.chung\end{matrix}\right.\\ \Rightarrow\Delta ABH=\Delta BDH\left(ch-gn\right)\\ \Rightarrow HA=HD\)

b, Xét tg AHE và tg DHC có

\(\left\{{}\begin{matrix}\widehat{AHE}=\widehat{DHC}\left(đối.đỉnh\right)\\\widehat{HAE}=\widehat{HDC}=90^0\\HA=HD\left(cmt\right)\end{matrix}\right.\\ \Rightarrow\Delta AHE=\Delta DHC\left(g.c.g\right)\\ \Rightarrow CD=AE\)

Mà \(AB=BD\left(\Delta ABH=\Delta DBH\right)\)

\(\Rightarrow AB+AE=BD+CD\\ \Rightarrow BE=BC\)

Vì \(AD=AB\) nên tg ABD cân tại B

Do đó \(\widehat{BAD}=\dfrac{180^0-\widehat{ABC}}{2}\left(1\right)\)

Vì \(BE=BC\) nên tg BEC cân tại B

Do đó \(\widehat{BEC}=\dfrac{180^0-\widehat{ABC}}{2}\left(2\right)\)

Từ \(\left(1\right)\left(2\right)\Rightarrow\widehat{BAD}=\widehat{BEC}\) mà 2 góc này ở vị trí đồng vị nên AD//EC

Bài j v e?

 

đề bài đâu ah

Bài nào j

I was born and grew up in a small village of DAI TU district, in THAI NGUYEN province. It is about 150 km from here.

It is a small village because it has only a population of 1000 with a size of 3 square kilometers

There is a  primary school in the village, so it is very convenient for children to go to school. There is a small market with a lot of fresh food. The food here is cheaper and fresher than the one in the city.

My village has some nice view, such as: large fields where we can fly a kite and Cau river, where I could swim and my mother usually wash clother there.

Centre of my village is a khuon ga pagoda, it has a large yard,where we usually play badminton, tabletenis or meet each other to chat, next to the pagoda is a large lake. I going fishing here very much.

Especially, I tea of my hometown a lot, because it very delecious, I usually drink a cup of tea before I start working.

The people in my village are very hospitable, friendly, helpful and generous. They are all hard working people. They mainly live on farming and business…

Being a learner of Tran quoc Tuan university, I only come home once a month , so I miss my hometown very much.

Life in the city is full of activity. Early in the morning hundreds of people rush out of their homes in the manner ants do when their nest is broken. Soon the streets are full of traffic. Shops and offices open, students flock to their schools and the day’s work begins. The city now throb with activity, and it is full of noise. Hundreds of sight-seers, tourists and others visit many places of interest in the city while businessmen from various parts of the world arrive to transact business.

Then towards evening, the offices and day schools begin to close. Many of the shops too close. There is now a rush for buses and other means of transport. Everyone seems to be in a hurry to reach home. As a result of this rush, many accidents occur. One who has not been to the city before finds it hard to move about at this time. Soon, however, there is almost no activity in several parts of the city. These parts are usually the business centres. With the coming of night, another kind of actịvity begins. The streets are now full of colorful lights. The air is cooler and life becomes more leisurely. People now seek entertainment. Many visit the cinemas, parks and clubs, while others remain indoors to watch television or listen to the radio. Some visit friends and relatives and some spend their time reading books and magazines. Those who are interested in polis discuss the latest polial developments. At the same time, hundreds of crimes are committed. Thieves and robbers who wait for the coming of night become active, and misfortune descends upon many. For the greed of a few, many are killed, and some live in constant fear. To bring criminals to juse, the officers of the law are always on the move.

Workers and others who seek advancement in their careers attend educational institutions which are open till late in the night. Hundreds of them sit for various examinations every year. The facilities and opportunities that the people in the city have to further their studies and increase their knowledge of human affairs are indeed many. As a result, the people of the city are usually better informed than those of the village, where even a newspaper is sometimes difficult to get.

The city could, therefore, be described as a place of ceaseless activity. Here, the drama of life is enacted every day.