Giải:
a)
$\displaystyle \frac{\sqrt{5} - \sqrt{3}}{\sqrt{2}} = \frac{(\sqrt{5} - \sqrt{3})\sqrt{2}}{2} = \frac{\sqrt{10} - \sqrt{6}}{2}$
b)
$\displaystyle \frac{26}{5 - 2\sqrt{3}} = \frac{26(5 + 2\sqrt{3})}{25 - 12} = \frac{26(5 + 2\sqrt{3})}{13} = 2(5 + 2\sqrt{3}) = 10 + 4\sqrt{3}$
c)
$\displaystyle \frac{2\sqrt{10} - 5}{4 - \sqrt{10}} = \frac{\sqrt{5}(2\sqrt{2} - \sqrt{5})}{\sqrt{2}(2\sqrt{2} - \sqrt{5})} = \frac{\sqrt{5}}{\sqrt{2}} = \frac{\sqrt{10}}{2}$
d)
$\displaystyle \frac{9 - 2\sqrt{3}}{3\sqrt{6} - 2\sqrt{2}} = \frac{\sqrt{3}(3\sqrt{3} - 2)}{\sqrt{2}(3\sqrt{3} - 2)} = \frac{\sqrt{3}}{\sqrt{2}} = \frac{\sqrt{6}}{2}$