\[\ \left( \sqrt{5} - \sqrt{3} \right)^{2} = 5 - 2\sqrt{15} + 3 = 8 - 2\sqrt{15}\]
\[\frac{1}{2} \cdot \sqrt{28} > \frac{1}{3}\sqrt{54}\]
\[\frac{1}{4} \cdot 28 > \frac{1}{9} \cdot 54\]
\[7 > 6.\]
\[\ \frac{\sqrt{10} + 5}{2 + \sqrt{10}} = \frac{\sqrt{5}\left( \sqrt{2} + \sqrt{5} \right)}{\sqrt{2}\left( \sqrt{2} + \sqrt{5} \right)} = \frac{\sqrt{5}}{\sqrt{}2} = \sqrt{2,5}\]