9) √(49/84) =

Сократим дробь под корнем: \(\frac{49}{84}=\frac{7}{12}\).

\(\sqrt{\frac{7}{12}}=\frac{\sqrt{84}}{12}=\frac{2\sqrt{21}}{12}=\frac{\sqrt{21}}{6}\).

Ответ: \(\frac{\sqrt{21}}{6}\).