`c, (2x - 1)^{3} = -8`
$\Rightarrow$ `(2x - 1)^{3} = (-2)^{3}`
$\Rightarrow$ `2x - 1 = -2`
$\Rightarrow$ `2x = -2 + 1`
$\Rightarrow$ `2x = -1`
$\Rightarrow$ `x = -1 : 2`
$\Rightarrow$ `x = -1/2`
$\text{Vậy}$ `x = -1/2`
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`d, (x + 1/2)^{2} = 1/16`
$\Rightarrow$ `(x + 1/2)^{2} = (1/4)^{2}`
$\Rightarrow$ `x + 1/2 = +- 1/4`
$\Rightarrow$ $\left[\begin{matrix} x+\dfrac{1}{2}=\dfrac{1}{4}\\ x+\dfrac{1}{2}=\dfrac{-1}{4}\end{matrix}\right.$
$\Rightarrow$ $\left[\begin{matrix} x=\dfrac{1}{4}-\dfrac{1}{2}\\ x=\dfrac{-1}{4}-\dfrac{1}{2}\end{matrix}\right.$
$\Rightarrow$ $\left[\begin{matrix} x=\dfrac{-1}{4}\\ x=\dfrac{-3}{4}\end{matrix}\right.$
$\text{Vậy}$ `x \in {-1/4 ; -3/4}`
