로그 식 값

$\displaystyle \log _{2} x + \log _{4} \frac{1}{x} = \log _{2} x - \log _{2} x ^{\frac{1}{2}}$$\displaystyle = \log _{2} x ^{\frac{1}{2}}$$\displaystyle = \frac{1}{2} \log _{2} x$$= 5$ ∴ $x = 2 ^{10}$ ……………………… ㉠ ∴ $\displaystyle \log _{4} x - \log _{2} \frac{1}{x} = \log _{2} x ^{\frac{1}{2}} + \log _{2} x$ $\displaystyle = \log _{2} x ^{\frac{3}{2}}$$= \log _{2} 2 ^{15}$ (∵ ㉠) $= 15$