Robots play a very important role in my life. There are many types ò robot such as: home robots, doctors robots, worker robots. Each robot há diffrerent uses. Home robots can do the housework. Doctor robots can help sick people. And worker robots can buid big buidings. And I will have a toy robot in the future. It will play and joke with me. 

# study well#

#huyentran#

Today robots can do a lot of things they couldn't before. In the past, robots could not teach; cannot communicate or take care of sick people. But now, teaching robots can teach simple lessons; Robots employees can serve, ask guests; Doctor robots have more types robo robots, super tiny robots, nurse robots that care for children with fever. And in the future, they can do more ...

TH1: 8-x=0

            x=8

TH2: x-19=0

         x     = 19

Vậy ....

\(\left(8-x\right)\left(x-19\right)=0\)

\(\Rightarrow\orbr{\begin{cases}8-x=0\\x-19=0\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x=8\\x=19\end{cases}}\)

=.= hk tốt!!

xin lỗi mọi người chót chứ hông phải chó

Mở bài: 

Người thân trong gia đình mà em quý nhất là bà của em. Bà của em rất tốt bụng, bà đã từng là 1 bác sĩ giỏi, người đã trải qua bao nhiêu khó khăn, chông gai trở ngại để mang lại niềm hạnh phúc cho người khác. Những việc tốt mà bà đã làm là vô hạn.

Kết bài: 

Bà là 1 thiên thần trong mắt mọ người, bà đã mang lại sự sống cho bao con người ốm yếu khác, ngay cả lúc người đó sắp ngừng thở, bà vẫn luôn cố gắng chữa trị cho đến giây phút cuối cùng. 

       Gọi ƯCLN ( 3n + 1 , 3n + 4 ) là d

 Xét hiệu :

              ( 3n + 4 ) - ( 3n + 1 ) \(⋮\)d

                         4 - 1 \(⋮\)d

                            3 \(⋮\)d

                           \(\rightarrow d\inƯ\left(3\right)\rightarrowƯ\left(3\right)=\left\{1,-1,-3,3\right\}\)

                           \(d\ne3\)vì \(3n+4⋮̸\)\(3\)

                              \(\rightarrow d=1,d=-1\)

                            Vậy ....

                                                  #Cothanhkhe

Gọi ƯCLN(3n+1;3n+4)=d

Suy ra 3n+1 và 3n+4 chia hết cho d

Suy ra (3n+4)-(3n+1) chia hết cho d 

                     3                 chia hết cho d

               suy ra d thuộc tợp hợp (+-1;+-3 )

mà 3n+1 ko chia hết cho d suy ra d=+-1 suy ra P/S đó là PS tối giản

Chúc học tốt

1.The girls are playing tennis at the moment

2.John always goes ro chool by car

3.What do you doin the afternoon ?

4.They are chatting in the class now

5.My sister doesn't buy a new car

1. at/ tennis/ The girls/ playing/ the moment/ are

=> The girls are playing tennis at the moment.

2. always/ by/ Jonh/ goes to/ car/ school

=> Jonh always goes to school by car.

3. do/ in/ What/ you/ the afternoon/ do/ ?

=> What do you do in the afternoon?

4. chatting/ the class/ are/ They/ in/ now

=> They are chatting in the class now.

5. doesn't/ a new car / buy/ sister/ My

=> My sister doesn't buy a new car.

1: -> Linh and her (his, my, our, their,...) parents are proud of him because he always gets good marks.

2: -> We are very interested in playing soccer when we live in the countryside.

3: -> I haven't talked to uncle since he bought a new house in the city center.

4: -> The Browns will buy a lot of food because they are going to have a party.

5: -> It only a small car so there're not enough room for all of us.

1. Linh's parents are very proud of him because he always gets good marks.

2. We were very interested in playing soccer when we lived in the countryside.

3. I haven't talked to my uncle since he bought a new house in the city center.

4. The Browns have bought a lot of food because they are going to have a party.

5. It is only a small car, so there is not enough room for all of us

Trả lời :

Khi nhiệt độ tăng thì khối lượng không đổi, trọng lượng không đổi, thể tích tăng, khối lượng riêng giảm, trọng lượng riêng giảm.

~ Study well ~

Đặt \(S=\frac{1}{3^2}+\frac{1}{4^2}+...+\frac{1}{100^2}\)

Ta có: \(\frac{1}{3^2}< \frac{1}{2.3}\)

           \(\frac{1}{4^2}< \frac{1}{3.4}\)

           . ....................

           \(\frac{1}{100^2}< \frac{1}{99.100}\)

\(\Rightarrow S< \frac{1}{2.3}+\frac{1}{3.4}+...+\frac{1}{99.100}\)

\(\Rightarrow S< \frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{99}-\frac{1}{100}\)

\(\Rightarrow S< \frac{1}{2}-\frac{1}{100}< \frac{1}{2}\)

\(\Rightarrow S< \frac{1}{2}\)

1/3^2 +1/4^2 +...+ 1/100^2 < 1/2.3+1/3.4+ 1/4.5 +...+ 1/99.100

1/3.3 +1/4.4 +...+ 1/100.100 < 1/2 -1/3 +1/3_1/4 +..+ 1/99-1/100

1/3.3 +1/4.4 +...+ 1/100.100 < 1/2 -1/100

1/3.3 +1/4.4 +...+ 1/100.100  < 50/100 -1/100

1/3.3 +1/4.4 +...+ 1/100.100   < 49/100

1/3.3 +1/4.4 +...+ 1/100.100 < 49/100 <50/100 = 1/2

\(\Rightarrow\)1/3^2 +1/4^2 +...+ 1/100^2    < 1/2