1/27 ≤ 3^{2-x}≤81 ?????

[latex]3^{2-x} \geq \frac{1}{27} \\ 3^{2-x} \geq 3^{-3} \\ 2-x \geq -3[/latex] [latex]3^{2-x} \leq 81 \\ 3^{2-x} \leq 3^4 \\ 2-x \leq 4[/latex] Имеем систему неравенства [latex] \left \{ {{2-x \geq -3} \atop {2-x \leq 4}} \right. \to \left \{ {{x \leq 5} \atop {x \geq -2}} \right. [/latex] Ответ: [latex]x \in [-2;5][/latex]