2) а) \(\frac{5}{\sqrt{4225}}-\sqrt{\frac{25}{169}}\); б) \(\frac{1}{\sqrt{361}}+\sqrt{6,25}\).

а) \(\sqrt{4225}=65\), а \(\sqrt{\frac{25}{169}}=\frac{5}{13}\). Тогда

\[\frac{5}{\sqrt{4225}}-\sqrt{\frac{25}{169}}=\frac{5}{65}-\frac{5}{13}=\frac{1}{13}-\frac{5}{13}=-\frac{4}{13}.\]

б) \(\sqrt{361}=19\), \(\sqrt{6,25}=2,5\). Следовательно,

\[\frac{1}{\sqrt{361}}+\sqrt{6,25}=\frac{1}{19}+2,5=\frac{1}{19}+\frac{5}{2}=\frac{97}{38}.\]

Ответ: а) \(-\frac{4}{13}\); б) \(\frac{97}{38}\).