Сократите дробь (9-a)/(3+ корень из a)

\[\mathbf{\ }\frac{9 - a}{3 + \sqrt{a}} = \frac{(3 - \sqrt{a})(3 + \sqrt{a})}{3 + \sqrt{a}} = 3 - \sqrt{a}\]

\[\ \frac{1}{2\sqrt{5}} = \frac{1}{2\sqrt{5}} \cdot \frac{\sqrt{5}}{\sqrt{5}} = \frac{\sqrt{5}}{10}\]