a, | x | - 5 = 3
| x | = 8
`=>` x ∈ { ±8 }
Vậy x ∈ { ±8 }
b, 15 - 2 | x | = 13
2 | x | = 2
| x | = 1
`=>` x ∈ { ±1 }
Vậy x ∈ { ±1 }
c, | x - 2 | = 0
`=>` x - 2 = 0
x = 2
Vậy x = 2
e, | x - 5 | = 7 + ( -3 )
| x - 5 | = 7 - 3
| x - 5 | = 4
`=>` \(\left[ \begin{array}{l}x-5=4\\x-5=-4\end{array} \right.\)
`=>` \(\left[ \begin{array}{l}x=9\\x=1\end{array} \right.\)
Vậy x ∈ { 1 ; 9 }
h, 123 - 5 | x + 4 | = 38
5 | x + 4 | = 85
| x + 4 | = 17
`=>` \(\left[ \begin{array}{l}x+4=17\\x+4=-17\end{array} \right.\)
`=>` \(\left[ \begin{array}{l}x=13\\x=-21\end{array} \right.\)
Vậy x ∈ { 13 ; -21 }
i, | -x + 8 | = -13 - ( -21 )
| -x + 8 | = -13 + 21
| -x + 8 | = 8
`=>` \(\left[ \begin{array}{l}-x-8=8\\-x-8=-8\end{array} \right.\)
`=>` \(\left[ \begin{array}{l}-x=16\\-x=0\end{array} \right.\)
`=>` \(\left[ \begin{array}{l}x=-16\\x=0\end{array} \right.\)
Vậy x ∈ { -16 ; 0 }
