Question

Tìm số tự nhiên x, biết:

a, 128 – 3( x + 4 ) = 23

b, [( 4x + 28 ).3 + 55] : 5 = 35

Answer 1

a) \(128-3\left(x+4\right)=23\)

\(\Rightarrow3\left(x+4\right)=128-23\)

\(\Rightarrow3\left(x+4\right)=105\)

\(\Rightarrow x+4=35\)

\(\Rightarrow x=35-4\)

\(\Rightarrow x=31\)

b) \(\left[\left(4x+28\right)\cdot3+55\right]:5=35\)

\(\Rightarrow\left(4x+28\right)\cdot3+55=35\cdot5\)

\(\Rightarrow\left(4x+28\right)\cdot3+55=175\)

\(\Rightarrow\left(4x+28\right)\cdot3=120\)

\(\Rightarrow4x+28=40\)

\(\Rightarrow4x=12\)

\(\Rightarrow x=3\)

Answer 2

a, \(128-3\left(x+4\right)=23\)

\(=>3\left(x+4\right)=128-23\)

\(=>3\left(x+4\right)=105\)

\(=>x+4=105:3\)

\(=>x+4=35\)

\(=>x=35-4\)

\(=>x=31\)

b, \(\left[\left(4x+28\right).3+55\right]:5=35\)

\(=>\left(4x+28\right).3+55=35.5\)

\(=>\left(4x+28\right).3+55=175\)

\(=>\left(4x+28\right).3=175-55\)

\(=>\left(4x+28\right).3=120\)

\(=>4x+28=120:3\)

\(=>4x+28=40\)

\(=>4x=40-28\)

\(=>4x=12\)

\(=>x=12:4\)

\(=>x=3\)

\(#WendyDang\)

Answer 3

a) 128 - 3 (x + 4) =23

      3.( x + 4) = 128 -23

      3. ( x + 4) =  105

      x + 4 = 105 :3

      x + 4 =  35

      x = 35 -4

     x = 31

 

  

Answer 4

`a, 128 - 3(x + 4) = 23`

`3(x + 4) = 128 - 23`

`3(x + 4) = 105`

`x + 4 = 105 : 3`

`x + 4 = 35`

`x = 35 - 4`

`x = 31`

Vậy `x = 31`

-----------------------------------

`b, [(4x + 28) . 3 + 55 ] : 5 = 35`

`(4x + 28) . 3 + 55 = 35 . 5`

`(4x + 28) . 3 + 55 = 175`

`(4x + 28) . 3 = 175 - 55`

`(4x + 28) . 3 = 120`

`4x + 28 = 120 : 3`

`4x + 28 = 40`

`4x = 40 - 28`

`4x = 12`

`x = 12 : 4`

`x = 3`

Vậy `x = 3`