로그부등식

진수는 양수이므로 $x > 0$ $\cdots \cdots$ ㉠ $\left( {\mathrm{\log}} \mathit{_{2}} x \right) ^{2} + {\mathrm{\log}} \mathit{_{2}} x - 2 \geq 0$에서 $\left. \left( \mathrm{\mathrm{\log}} \mathit{\mathit{_{2}}} x + 2 \right) \left( \mathrm{\mathrm{\log}} \mathit{\mathit{_{2}}} x - 1 \right) \geq 0 \right.$$\leftrightarrow$$\mathrm{\mathrm{\log}} \mathit{\mathit{_{2}}} x \leq - 2$ 또는 ${\mathrm{\log}} \mathit{_{2}} x \geq 1$ $\displaystyle {\mathrm{\log}} \mathit{_{2}} x \leq {\mathrm{\log}} \mathit{_{2}} \frac{1}{4}$ 또는 ${\mathrm{\log}} \mathit{_{2}} x \geq {\mathrm{\log}} \mathit{_{2}} 2$ ∴ $\displaystyle x \leq \frac{1}{4}$ 또는 $x \geq 2$ $\cdots \cdots$ ㉡ ㉠, ㉡에서 $\displaystyle 0 < x \leq \frac{1}{4}$ 또는 $x \geq 2$