№ 8. 5) \(\dfrac{\sqrt{65}\cdot\sqrt{13}}{\sqrt{5}}\) и \(\dfrac{\sqrt{35}\cdot\sqrt{21}}{\sqrt{15}}\).

1. \(\dfrac{\sqrt{65}\cdot\sqrt{13}}{\sqrt{5}}=\sqrt{\dfrac{65\cdot13}{5}}=\sqrt{169}=13\).
2. \(\dfrac{\sqrt{35}\cdot\sqrt{21}}{\sqrt{15}}=\sqrt{\dfrac{35\cdot21}{15}}=\sqrt{49}=7\).

Ответ: 13 и 7.