`(2x + 1)^{2} - 2 = |-14|`
$\Leftrightarrow$ `(2x + 1)^{2} - 2 = 14`
$\Leftrightarrow$ `(2x + 1)^{2} = 14 + 2`
$\Leftrightarrow$ `(2x + 1)^{2} = 16`
$\Leftrightarrow$ `(2x + 1)^{2} = (+- 4)^{2}`
$\Leftrightarrow$ `2x + 1 = +- 4`
$\Leftrightarrow$ $\left[\begin{matrix} 2x+1=4\\ 2x+1=-4\end{matrix}\right.$
$\Leftrightarrow$ $\left[\begin{matrix} 2x=4-1\\ 2x=-4-1\end{matrix}\right.$
$\Leftrightarrow$ $\left[\begin{matrix} 2x=3\\ 2x=-5\end{matrix}\right.$
$\Leftrightarrow$ $\left[\begin{matrix} x=3:2\\ x=-5:2\end{matrix}\right.$
$\Leftrightarrow$ $\left[\begin{matrix} x=\dfrac{3}{2}\\ x=\dfrac{-5}{2}\end{matrix}\right.$
$\text{Vậy}$ `x \in {3/2 ; {-5}/2}`
