4^x+2-15=49

4^x+2      =49+15

4^x+2      =64

4^x+2      =4³

4^x         =4^3-2

4^x         =4¹

⇒x        =1

\(4^{x+2}=49+15\\ 4^{x+2}=64\\ 4^{x+2}=4^3\\ 4^x=4^{3-2}\\ 4^x=4^1\\ \Rightarrow x=1\)

\(\left(7x-15\right)\times8-21=27\\ \Rightarrow\left(7x-15\right)\times8=27+21\\ \Rightarrow\left(7x-15\right)\times8=48\\ \Rightarrow7x-15=48:8\\ \Rightarrow7x-15=6\\ \Rightarrow7x=15+6\\ \Rightarrow7x=21\\ \Rightarrow x=3\)

 (7x - 15 )  . 8 - 21 = 27                                                                                                                                                                                      (7x - 15 )  . 8        = 27+21
       7x - 15                 = 48 : 8                                                                                                                                                                                 7x                        = 6 + 15                                                                                                                                                                                  x                        = 21 : 7 = 3    

Tính hợp lí nha mn

giúp mình nha mình cần gấp

5.There are four people in her family.
Her family has four people
6.My house is behind the hotel.
The hotel is in front of my house
7.Does your class have twenty­five students ?
Are there twenty-­five students in your class .

Hơi lừi :3
 

6. My house is behind the hotel.

The hotel is in front of my house

7. Does your class have twenty - five students ?

Are there twenty - five students in your class ?

8. My room is smaller than your room.

Your room is bigger than my room

9. How many classes are there in your school?

How many classes does your school have ?

10. That class room is small.

That is a small classroom

11. Peter is Mary's brother.

Mary is Peter’s sister

12. My house has four floors.

There are four floors in my house

13. Mr. and Mrs. Black have a son, John.

John is a son of Mr. and Mrs. Black

14. My school has six hundred students.

There are six hundred students in my school

15. The supermarket is behind the bank.

The bank is in front of the supermarket

16. How much is a bottle of cooking oil ?

How much doesa bottle of cooking oil cost ?

17. Nga usually walks to school.

Nga usually goes to school on foot

18. What time does she go to work ?

When does she go to work ?

19. She likes noodles.

Her favourite food is noodles

30. What is the price of these apples ?

How much is the price of these apples ?

20. Does Phong's school have forty classrooms ?

Are there forty classrooms in Phong's school ?

Để $2n+1=2\left(n+2\right)-3⋮n+2$

$\Rightarrow 3⋮n+2$

$\Rightarrow n+2=Ư\left(3\right)=\left\{-3;-1;1;3\right\}$

$\Rightarrow n=\left\{-1;1;3;5\right\}$

Đề là gì v ? Ghi rõ ra tí đk ?

thoi

24 . (-25) = -600                                         (-15) . 12 = -180

24*(-25)= -600

(-15)*12 = -180

Ta có:
+\(\dfrac{-15}{3}=-5\) (1)

+\(\dfrac{21}{7}=3\) (2)

Từ (1), (2) => \(-\dfrac{15}{3}< x\le\dfrac{21}{7}\Leftrightarrow-5< x\le3\)

mà \(x\inℤ\)

=> \(x\in\left\{-4;-3;-2;-1;0;1;2;3\right\}\)

sao thế chưa ai giúp hả em???

(x-1)y = 2

\(\left[{}\begin{matrix}\left\{{}\begin{matrix}x-1=1\\y=2\end{matrix}\right.\\\left\{{}\begin{matrix}x-1=2\\y=1\end{matrix}\right.\\\left\{{}\begin{matrix}x-1=-1\\y=-2\end{matrix}\right.\\\left\{{}\begin{matrix}x-1=-2\\y=-1\end{matrix}\right.\end{matrix}\right.\)

\(\left[{}\begin{matrix}\left\{{}\begin{matrix}x=2\\y=2\end{matrix}\right.\\\left\{{}\begin{matrix}x=3\\y=1\end{matrix}\right.\\\left\{{}\begin{matrix}x=0\\y=-2\end{matrix}\right.\\\left\{{}\begin{matrix}x=-1\\y=-1\end{matrix}\right.\end{matrix}\right.\)