i, 2 . | x - 3 | + 4 = 6
2 . | x - 3 | = 2
| x - 3 | = 1
`=>` \(\left[ \begin{array}{l}x-3=1\\x-3=-1\end{array} \right.\)
`=>` \(\left[ \begin{array}{l}x=4\\x=2\end{array} \right.\)
Vậy x ∈ { 2 ; 4 }
j, 27 - 3 . | 2x - 4 | = 3
3 . | 2x - 4 | = 9
| 2x - 4 | = 3
`=>` \(\left[ \begin{array}{l}2x-4=3\\2x-4=-3\end{array} \right.\)
`=>` \(\left[ \begin{array}{l}2x=7\\2x=1\end{array} \right.\)
`=>` \(\left[ \begin{array}{l}x=\frac{7}{2}\\x=\frac{1}{2}\end{array} \right.\)
Vậy x ∈ { `7/2` ; `1/2` }
k, | 2x + 4 | = x - 4
`=>` \(\left[ \begin{array}{l}2x+4=x-4\\2x+4=4-x\end{array} \right.\)
`=>` \(\left[ \begin{array}{l}2x-x=-4-4\\2x+x=4-4\end{array} \right.\)
`=>` \(\left[ \begin{array}{l}x=-8\\x=0\end{array} \right.\)
Vậy x ∈ { -8 ; 0 }
