Question

tìm x biết :

a. 41 - 5x = 31       

b. 72 - ( 3x - 15 ) = 21

Answer 1

Tìm x biết:

a. 41 - 5x = 31

5x = 41 - 31

5x = 10

x = 10 : 5

x = 2

b. 72 - (3x - 15) = 21

(3x - 15) = 72 - 21

(3x - 15) = 51

3x = 51 + 15

3x = 66

x = 66 : 3

x = 22.

Answer 2

\(a.5x=41-31\\ 5x=10\\ x=10:5\\ x=2\)

\(b,3x-15=72-21\\ 3x-15=51\\ 3x=51+15\\ 3x=66\\ x=66:3\\ x=22\)

 

 

Answer 3

`a. 41 - 5x = 31  `

`=> 5x = 41 - 31 =10`

`=> x =10/5 =2`

Vậy `x=2`     

`b. 72 - ( 3x - 15 ) = 21`

`<=> 3x-15 = 72-21 =51`

`=> 3x = 51 +15 = 66 `

`=> x = 66/3 = 22`

Vậy `x=22`