Ответ:

  1. \(\frac{2}{3}\sqrt{90}=\frac{2}{3}\cdot3\sqrt{10}=2\sqrt{10}\).
  2. \(\frac{6}{7}\sqrt{98}=\frac{6}{7}\cdot7\sqrt{2}=6\sqrt{2}\).
  3. \(1{,}75\sqrt{48}=\frac{7}{4}\cdot4\sqrt{3}=7\sqrt{3}\).
  4. \(2{,}25\sqrt{80}=\frac{9}{4}\cdot4\sqrt{5}=9\sqrt{5}\).
  5. \(\frac{1}{7}\sqrt{147}=\frac{1}{7}\cdot7\sqrt{3}=\sqrt{3}\).
  6. \(\frac{1}{6}\sqrt{216}=\frac{1}{6}\cdot6\sqrt{6}=\sqrt{6}\).