8. \(\dfrac{7\sqrt{8}}{\sqrt{98}}\)

Упростим корни: \(\sqrt{8}=2\sqrt{2}\), \(\sqrt{98}=7\sqrt{2}\).

\(\dfrac{7\sqrt{8}}{\sqrt{98}}=\dfrac{7\cdot2\sqrt{2}}{7\sqrt{2}}=2\).

Ответ: 2