Сравните: 7*корень из (1/7) и 1/2*корень из 20.

\[7\sqrt{\frac{1}{7}} = \sqrt{49 \cdot \frac{1}{7}} = \sqrt{7};\]

\[\frac{1}{2}\sqrt{20} = \sqrt{\frac{1}{4} \cdot 20} = \sqrt{5}.\]

\[\sqrt{7} > \sqrt{5};\]

\[7\sqrt{\frac{1}{7}} > \frac{1}{2}\sqrt{20}.\]