[tex]a) \ \frac{2}{\sqrt{5}} = \frac{2}{\sqrt{5}}\cdot\frac{\sqrt{5}}{\sqrt{5}} = \frac{2\sqrt{5}}{5}\\\\\\b) \ \frac{4}{3\sqrt{2}} = \frac{4}{3\sqrt{2}}\cdot\frac{\sqrt{2}}{\sqrt{2}} = \frac{4\sqrt{2}}{3\cdot2} = \frac{2\sqrt{2}}{3}[/tex]
