\[(a + 2)x \leq a^{2} - 4\]
\[a = - 2 \Longrightarrow ( - \infty; + \infty)\]
\[a < - 2 \Longrightarrow x \geq \frac{(a - 2)(a + 2)}{a + 2},\]
\[x \geq a - 2\]
\[a > - 2 \Longrightarrow x \leq a - 2.\]