1, [(4.x-28)] . 3+55] : 5= 35 2, (3.x-2^4).7^3 = 2.7^4 3, 43+(9.21)=317-(x+317)

Giải thích các bước giải:

`1, [ (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 =68`

`x= 68 : 4`

`x =17`

` Vậy  x=17`

`2, ( 3x - 2^4 ) . 7^3 = 2 . 7^4`

`3x - 16 = (2. 7^4)/(7^3)`

` 3x - 16 = 14`

`3x = 14 + 16`

`3x =30`

`x= 30 : 3`

`x=10`

` Vậy  x=10`

`3, 43 + (9.21) = 317 - ( x+317)`

`43 + 189 = 317 - 317 -x `

`0-x = 232`

`x = 0-232`

`x = -232`

` Vậy  x=-232`

$\text{1) {[( 4x - 28 )] × 3 + 55} : 5 = 35 }$

$\text{[( 4x - 28 )] × 3 + 55 = 35 × 5 }$

$\text{[( 4x - 28 )] × 3 + 55 = 175 }$

$\text{[( 4x - 28 )] × 3 = 175 - 55 }$

$\text{[( 4x - 28 )] × 3 = 120 }$

$\text{4x - 28  = 120 : 3 }$

$\text{4x - 28  = 40 }$

$\text{4x = 40 + 28 }$

$\text{4x = 68 }$

$\text{x = 68 : 4 }$

$\text{x = 17 }$

$\text{Vậy x = 17}$

$\text{2) ( 3x - $2^{4}$ ) × $7^{3}$ = 2 × $7^{4}$}$

$\text{( 3x - $2^{4}$ ) × $7^{3}$ = 2 × 7 × $7^{3}$}$

$\text{⇒ 3x - $2^{4}$ = 2 × 7 }$

$\text{3x - 16 = 14 }$

$\text{3x = 16 + 14 }$

$\text{3x = 30 }$

$\text{x = 30 : 3 }$

$\text{x = 10 }$

$\text{Vậy x = 10 }$

$\text{3) 43 + ( 9 × 21 ) = 317 - ( x + 317 )}$

$\text{43 + 189 = 317 - x - 317 }$

$\text{232 = 317 - 317 - x }$

$\text{232 = 0 - x }$

$\text{232 = -x }$

$\text{⇒ x = -232}$

$\text{Vậy x = -232}$