Các bước giải:
`|x +1/2| = 4`
$⇒ \left[ \begin{array}{l}x +\dfrac{1}{2}=4\\x +\dfrac{1}{2}=-4\end{array} \right. ⇒ \left[ \begin{array}{l}x=\dfrac{7}{2}\\x=\dfrac{-9}{2}\end{array} \right.$
Vậy `x ∈ {7/2; -9/2}`
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`|x -1| = 69`
$⇒ \left[ \begin{array}{l}x -1=69\\x -1=-69\end{array} \right. ⇒ \left[ \begin{array}{l}x=70\\x=-68\end{array} \right.$
Vậy `x ∈ {70; -68}`
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`|x.4³| = 20`
`⇒ |64.x| = 20`
$⇒ \left[ \begin{array}{l}64.x=20\\64.x=-20\end{array} \right. ⇒ \left[ \begin{array}{l}x=\dfrac{5}{16}\\x=\dfrac{-5}{16}\end{array} \right.$
Vậy `x ∈ {5/16; -5/16}`
