$\begin{array}{l} D = \left\{ {x \in \mathbb{Q}|\left( {2x - 1} \right)\left( {{x^2} - 4} \right) = 0} \right\}\\ \Rightarrow \left( {2x - 1} \right)\left( {{x^2} - 4} \right) = 0\\ \Leftrightarrow \left( {2x - 1} \right)\left( {x - 2} \right)\left( {x + 2} \right) = 0\\ \Leftrightarrow \left[ \begin{array}{l} x = \dfrac{1}{2}\\ x = 2\\ x = - 2 \end{array} \right. \end{array}$
Mà $x\in \mathbb{Q}$ nên $D = \left\{ { - \dfrac{1}{2};2; - 2} \right\}$
$\begin{array}{l} E = \left\{ {2k + 1| - 5 \le k < 1,k \in \mathbb{Z}} \right\}\\ \Rightarrow k \in \left\{ { - 5; - 4; - 3; - 2; - 1;0} \right\}\\ E = \left\{ { - 9; - 7; - 5; - 3; - 1;1} \right\} \end{array}$
