` 1)`
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`
`[( 4 . x +28 ) . 3 + 55 ] = 35 =>` Câu này mk nghĩ là đề sai
`( 12 . x - 4^3 ) . 8^3 = 4 . 8^4`
`=> ( 12 . x - 4^3 ) = 4 . 8`
`=> ( 12 . x - 64 ) = 32`
`=> 12 .x = 32 + 64`
`=> 12 . x = 96`
`=>x = 96 : 12`
`=> x = 8`
`720 : [ 41 - ( 2 . x - 5 )] = 2^3 . 5`
`=> 41 - ( 2x - 5 ) = 720 : 40`
`=> 41 - ( 2x - 5 ) = 18`
`=> 2x - 5 = 41 - 18`
`=> 2x - 5 = 23`
`=> 2x = 23 + 5`
`=> 2x = 28`
`=> x = 28 : 2`
`=> x = 14`
b ,
Ta có` : ( x . 5 + 16 ) : 3 = 7`
` => x . 5 + 16 = 3 . 7 = 21`
` => x . 5 = 21 - 16 = 5`
` => x = 1 `
c , Ta có : `( x : 3 - 4 ) . 5 = 15`
`=> x : 3 - 4 = 3`
`=> x : 3 = 7`
`=>x = 21`