Сократите дробь (b-4)/(корень из b-2)

\[\ \frac{b - 4}{\sqrt{b} - 2} = \frac{\left( \sqrt{b} - 2 \right)\left( \sqrt{b} + 2 \right)}{\sqrt{b} - 2} = \sqrt{b} + 2\ \]

\[\frac{2}{3\sqrt{7}} = \frac{2}{3\sqrt{7}} \cdot \frac{\sqrt{7}}{\sqrt{7}} = \frac{2\sqrt{7}}{21}\]