sqrt((4)/(9))= sqrt((1)/(18))= sqrt((25)/(36))=(5)/(6) sqrt((49)/(81))=(7)/(9)

$\sqrt{\frac{4}{9}} = \frac{\sqrt{4}}{\sqrt{9}} = \frac{2}{3}$<br /><br />$\sqrt{\frac{1}{18}} = \frac{\sqrt{1}}{\sqrt{18}} = \frac{1}{\sqrt{9 \times 2}} = \frac{1}{3\sqrt{2}} = \frac{\sqrt{2}}{6}$<br />