`a) 128 - 3 . ( x + 4 ) = 25`
`3. ( x + 4 ) = 128 - 25 `
`3 . (x + 4 ) = 103`
`x + 4 = 103 : 3 `
`x + 4 = 103/3 `
`x = 103/3 - 4 `
`x= 91/3`
`) 15 - 5 . | x + 4 | = -12 -3`
`15 - 5 . | x + 4 | = -15 `
`5.|x + 4 | = 15 - ( - 15 ) `
`5 | x + 4 | = 30 `
`x + 4 = 30 : 5 `
`x + 4= 6 ` hoặc ` x + 4 = - 6 `
`x = 6 - 4 ` ` x = - 6 - 4 `
`x = 2 ` `x = -10`
vậy ` x \in { 2 ; - 10 }`
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