`( m + 4 )^2 - 12 > 0`
`<=> ( m + 4 )^2 > 12`
`<=> | m + 4 | > 2\sqrt{3}`
`<=>` $\left[\begin{matrix} m + 4 \le -2\sqrt{3}\\ m + 4 \ge 2\sqrt{3}\end{matrix}\right.$
`<=>` $\left[\begin{matrix} m \le -2\sqrt{3} - 4\\ m \ge 2\sqrt{3} - 4\end{matrix}\right.$
Vậy `S = { m | m <= -2\sqrt{3} - 4\text{ hoặc } m >= 2\sqrt{3} - 4 }`