Không có gì đâu ạ !

Ta có:

\(-7x-3x\\ =\left(-7-3\right)x\\ =-10x\)

    Vậy \(-7x-3x=-10x\)

Ta có:
\(-4x-5x=3x-2x\\ \Leftrightarrow0=3x-2x+5x+4x\\ \Leftrightarrow0=10x\\ \Leftrightarrow x=0\)

     Vậy \(x=0\)

1, The sun rises in the east.

2, Water boils at 100 degrees.

3, The Olympic Games take place every four years.

4, Conan solves crimes every day.

5, I always brush my teeth before I go to bed.

1. woke 

2. was shining 

3. were singing 

4. was 

5. went 

6. was having 

7. said 

8. continued 

9. put  

10. opened 

11. was getting 

12. rang 

13. answered 

14. was practising 

1. How luxurious the car is!

2. I spend an hour doing/to do my home work every evening

3. I am the fastest runner.

4. Does your school have a library?

5. What is your age?

6. Would you like a cup of tea?

7.I don’t working so hard as my sister does.

8. Is this the best refrigerator you have?

9. It is not easy to find an apartment in a big city.

10.There are 28 days in February.

a, Ta có: \(\dfrac{x}{5}=\dfrac{y}{6};\dfrac{ y}{8}=\dfrac{z}{11}\Rightarrow \dfrac{x}{40}=\dfrac{y}{48}=\dfrac{z}{66}\)

                                      Và \(x+y-z=44\)

    Áp dụng tính chất dãy tỉ số bằng nhau ta có :

  \(\dfrac{x}{40}=\dfrac{y}{48}=\dfrac{z}{66}=\dfrac{x+y-z}{40+48-66}=\dfrac{44}{22}=2\\ \Rightarrow\left\{{}\begin{matrix}x=2.40\\y=2.48\\z=2.66\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}x=80\\y=96\\z=132\end{matrix}\right.\)

    Vậy\(\left\{{}\begin{matrix}x=80\\y=96\\z=132\end{matrix}\right.\)

b, Ta có: \(3x=8y \Rightarrow \dfrac{x}{8}=\dfrac{y}{3}\)

                Và \(x-2y=4\)

     Áp dụng tính chất dãy tỉ số bằng nhau ta có :

    \(\dfrac{x}{8}=\dfrac{y}{3}=\dfrac{x-2y}{8-6}=\dfrac{4}{2}=2\\ \Rightarrow\left\{{}\begin{matrix}x=2.8\\y=2.3\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}x=16\\y=6\end{matrix}\right.\)

    Vậy \(\left\{{}\begin{matrix}x=16\\y=6\end{matrix}\right.\)

Nhiều zữ z

A.Yes, you may

invention