Đáp án:
1) $S = \left( { - \infty ;0} \right) \cup \left( {3 + \sqrt 6 ; + \infty } \right) \cup \left( {3 - \sqrt 6 ;2} \right) \cup \left( {1;2} \right)$
2) $S = \left( { - \dfrac{{11}}{4}; + \infty } \right)\backslash \left\{ { - 2} \right\}$
3)$S = \left( { - \infty ;\dfrac{{19}}{{10}}} \right)$
Giải thích các bước giải:
$\begin{array}{l}
1)\left| {\dfrac{{4x - 3}}{{x - 2}}} \right| > x\left( {DK:x \ne 2} \right)\\
\Leftrightarrow \left[ \begin{array}{l}
x < 0\\
\left\{ \begin{array}{l}
x \ge 0\\
\left[ \begin{array}{l}
\dfrac{{4x - 3}}{{x - 2}} > x\\
\dfrac{{4x - 3}}{{x - 2}} < - x
\end{array} \right.
\end{array} \right.
\end{array} \right. \Leftrightarrow \left[ \begin{array}{l}
x < 0\\
\left\{ \begin{array}{l}
x \ge 0\\
\left[ \begin{array}{l}
\dfrac{{ - {x^2} + 6x - 3}}{{x - 2}} > 0\\
\dfrac{{{x^2} + 2x - 3}}{{x - 2}} < 0
\end{array} \right.
\end{array} \right.
\end{array} \right.\\
\Leftrightarrow \left[ \begin{array}{l}
x < 0\\
\left\{ \begin{array}{l}
x \ge 0\\
\left[ \begin{array}{l}
\left\{ \begin{array}{l}
- {x^2} + 6x - 3 > 0\\
x - 2 > 0
\end{array} \right.\\
\left\{ \begin{array}{l}
- {x^2} + 6x - 3 < 0\\
x - 2 < 0
\end{array} \right.\\
\left\{ \begin{array}{l}
{x^2} + 2x - 3 > 0\\
x - 2 < 0
\end{array} \right.\\
\left\{ \begin{array}{l}
{x^2} + 2x - 3 < 0\\
x - 2 > 0
\end{array} \right.
\end{array} \right.
\end{array} \right.
\end{array} \right. \Leftrightarrow \left[ \begin{array}{l}
x < 0\\
\left\{ \begin{array}{l}
x \ge 0\\
\left[ \begin{array}{l}
\left\{ \begin{array}{l}
\left[ \begin{array}{l}
x > 3 + \sqrt 6 \\
x < 3 - \sqrt 6
\end{array} \right.\\
x > 2
\end{array} \right.\\
\left\{ \begin{array}{l}
3 - \sqrt 6 < x < 3 + \sqrt 6 \\
x < 2
\end{array} \right.\\
\left\{ \begin{array}{l}
\left[ \begin{array}{l}
x > 1\\
x < - 3
\end{array} \right.\\
x < 2
\end{array} \right.\\
\left\{ \begin{array}{l}
- 3 < x < 1\\
x > 2
\end{array} \right.\left( {vn} \right)
\end{array} \right.
\end{array} \right.
\end{array} \right.\\
\Leftrightarrow \left[ \begin{array}{l}
x < 0\\
\left\{ \begin{array}{l}
x \ge 0\\
\left[ \begin{array}{l}
x > 3 + \sqrt 6 \\
3 - \sqrt 6 < x < 2\\
1 < x < 2\\
x < - 3
\end{array} \right.
\end{array} \right.
\end{array} \right. \Leftrightarrow \left[ \begin{array}{l}
x < 0\\
x > 3 + \sqrt 6 \\
3 - \sqrt 6 < x < 2\\
1 < x < 2
\end{array} \right.
\end{array}$
Vậy tập nghiệm của bất phương trình là: $S = \left( { - \infty ;0} \right) \cup \left( {3 + \sqrt 6 ; + \infty } \right) \cup \left( {3 - \sqrt 6 ;2} \right) \cup \left( {1;2} \right)$
$\begin{array}{l}
b)\dfrac{{ - 3}}{{{{\left( {x + 2} \right)}^2}}} < \dfrac{4}{{x + 2}}\left( {DK:x \ne - 2} \right)\\
\Leftrightarrow \dfrac{3}{{{{\left( {x + 2} \right)}^2}}} + \dfrac{4}{{x + 2}} > 0\\
\Leftrightarrow \dfrac{{3 + 4\left( {x + 2} \right)}}{{{{\left( {x + 2} \right)}^2}}} > 0\\
\Rightarrow 3 + 4\left( {x + 2} \right) > 0\\
\Leftrightarrow x > - \dfrac{{11}}{4}
\end{array}$
Vậy tập nghiệm của bất phương trình là:$S = \left( { - \dfrac{{11}}{4}; + \infty } \right)\backslash \left\{ { - 2} \right\}$
$\begin{array}{l}
3) - 2x + \dfrac{3}{5} > \dfrac{{3\left( {2x - 7} \right)}}{3}\\
\Leftrightarrow - 2x + \dfrac{3}{5} > 2x - 7\\
\Leftrightarrow 4x < \dfrac{{38}}{5}\\
\Leftrightarrow x < \dfrac{{19}}{{10}}
\end{array}$
Vậy tập nghiệm của bất phương trình là:$S = \left( { - \infty ;\dfrac{{19}}{{10}}} \right)$