Đáp án:
$\begin{array}{l}
a)\left( {x + 2} \right)\left( {x - 3} \right) = 0\\
\Rightarrow \left[ \begin{array}{l}
x + 2 = 0\\
x - 3 = 0
\end{array} \right.\\
\Rightarrow \left[ \begin{array}{l}
x = - 2\\
x = 3
\end{array} \right.\\
Vậy\,x \in \left\{ { - 2;3} \right\}\\
b)\left| {x - 2} \right| = 2x - 10\\
\Rightarrow \left[ \begin{array}{l}
x - 2 = 2x - 10\\
x - 2 = - 2x + 10
\end{array} \right.\\
\Rightarrow \left[ \begin{array}{l}
2x - x = - 2 + 10\\
x + 2x = 10 + 2
\end{array} \right.\\
\Rightarrow \left[ \begin{array}{l}
x = 8\\
3x = 12
\end{array} \right.\\
\Rightarrow \left[ \begin{array}{l}
x = 8\\
x = 4
\end{array} \right.\\
Vậy\,x \in \left\{ {4;8} \right\}\\
a)3x + 4 > 0\\
\Rightarrow 3x > - 4\\
\Rightarrow x > \dfrac{{ - 4}}{3}
\end{array}$
Em tự biểu diễn trên trục số nhé.
