``Bài 1 : Tìm `x ` , biết :

a ) 123 - 5 (`x ` + 4 ) = 38

b ) [( 6`x ` - 72 ) : 2 - 84 ] . 24 = 5688

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

d ) ( 4`x ` - `1 )^3 ` = `27^2 `

e ) 720 : [ 45 - ( 5 - 2`x `)^3 ] = `2^3 ` . 5

f ) 2022 + 2 ( `x ` - 1 ) = 2024

làm bài rất lâu vì vậy mong được hay nhất

`a ) 123 - 5 (x + 4 ) = 38`

`=>5 (x + 4 ) = 123 -38`

`=> 5(x+4)=85`

`=> x+4 = 85 : 5`

`=> x+4 =17`

`=> x=17-4`

`=> x=13`

vậy `x=13`

`b ) [( 6x  - 72 ) : 2 - 84 ] . 24 = 5688`

`=>( 6x  - 72 ) : 2 - 84=5688 : 24`

`=>( 6x  - 72 ) : 2 - 84=237`

`=>( 6x  - 72 ) : 2 =237+84`

`=> ( 6x  - 72 ) : 2 =321`

`=> 6x -72 =321. 2`

`=> 6x-72=642`

`=> 6x =714`

`=> x=119`

vậy `x=119`

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

`=> (3x-2^4) . 7^3 = 2. 2401`

`=>(3x-2^4) . 7^3 = 4802`

`=> (3x-2^4) . 342=4802`

`=> 3x -2^4 = 4802 : 342`

`=> 3x-2^4 =14`

`=> 3x - 16=14`

`=> 3x=30`

`=> x=10`

vậy `x=10`

`d, (4x-1)^3=27^2`

`=> (4x-1)^3 =729`

`=> (4x-1)^3=9^3`

`=> 4x-1=9`

`=> 4x=10`

`=> x=5/2`

vậy `x=5/2`

`e, 720 : [ 45 - (5 -2x)^3 ] =2^3 .5`

`=>720 : [ 45 - (5 -2x)^3 ] = 8.5`

`=>720 : [ 45 - (5 -2x)^3 ] =40`

`=> 45 -(5-2x)^3=720 : 40`

`=> 45 -(5-2x)^3=18`

`=> (5-2x)^3=45-18`

`=> (5-2x)^3=27`

`=>(5-2x)^3=3^3`

`=>5-2x=3`

`=>2x=5-3`

`=>2x=2`

`=>x=1`

vậy `x=1`

`f, 2022 + 2(x-1)=2024`

`=>2(x-1)=2024-2022`

`=>2(x-1)=2`

`=>x-1=2:2`

`=>x-1=1`

`=>x=1+1`

`=>x=2`

vậy `x=2`