Giải thích các bước giải:
\(\begin{array}{l}
a,\\
5{x^2} - 4x - 12 > 0\\
\Leftrightarrow \left( {x - 2} \right)\left( {5x + 6} \right) > 0\\
\Leftrightarrow \left[ \begin{array}{l}
x > 2\\
x < - \frac{6}{5}
\end{array} \right.\\
b,\\
- 16{x^2} + 40x - 25 > 0\\
\Leftrightarrow 16{x^2} - 40x + 25 < 0\\
\Leftrightarrow {\left( {4x - 5} \right)^2} < 0\,\,\,\,\,\left( {vn} \right)\\
c,\\
3{x^2} - 4x + 1 \le 0\\
\Leftrightarrow \left( {x - 1} \right)\left( {3x - 1} \right) \le 0\\
\Leftrightarrow \frac{1}{3} \le x \le 1\\
d,\\
{x^2} - x - 12 \ge 12\\
\Leftrightarrow \left( {x - 4} \right)\left( {x + 3} \right) \ge 12\\
\Leftrightarrow \left[ \begin{array}{l}
x \ge 4\\
x \le - 3
\end{array} \right.
\end{array}\)
