Ответ:

  1. \(2\sqrt{75}=2\sqrt{25\cdot3}=2\cdot5\sqrt3=10\sqrt3\).
  2. \(-100\sqrt{0.08}=-100\sqrt{\frac{2}{25}}=-100\cdot\frac{\sqrt2}{5}=-20\sqrt2\).
  3. \(\frac23\sqrt{6\frac34}=\frac23\sqrt{\frac{27}{4}}=\frac23\cdot\frac{3\sqrt3}{2}=\sqrt3\).

Ответ: 1) \(10\sqrt3\); 2) \(-20\sqrt2\); 3) \(\sqrt3\).