2) \(\frac{\sqrt{35} \cdot \sqrt{21}}{\sqrt{15}}\)

1. \(\frac{\sqrt{5 \cdot 7} \cdot \sqrt{3 \cdot 7}}{\sqrt{3 \cdot 5}}\) = \(\frac{\sqrt{5} \cdot \sqrt{7} \cdot \sqrt{3} \cdot \sqrt{7}}{\sqrt{3} \cdot \sqrt{5}}\).
2. \(\sqrt{7}\) \(\cdot\) \(\sqrt{7}\) = 7.
3. \(\text{Ответ: }\) 7.