14. $$log_2 \frac{1}{\sqrt[4]{2}}$$

$$log_2 \frac{1}{\sqrt[4]{2}} = log_2 2^{-\frac{1}{4}} = -\frac{1}{4}log_2 2 = -\frac{1}{4} \cdot 1 = -\frac{1}{4}$$

Ответ: $$-\frac{1}{4}$$