Ответ:

  1. \(\sqrt{72}=\sqrt{36\cdot2}=6\sqrt2\).
  2. \(\sqrt{80}=\sqrt{16\cdot5}=4\sqrt5\).
  3. \(\sqrt{300}=\sqrt{100\cdot3}=10\sqrt3\).
  4. \(\sqrt{0{,}98}=\sqrt{98/100}=\sqrt{49\cdot2}/10=7\sqrt2/10\).
  5. \(\frac12\sqrt{44}=\frac12\cdot2\sqrt{11}=\sqrt{11}\).
  6. \(-2{,}4\sqrt{75}=-2{,}4\cdot5\sqrt3=-12\sqrt3\).
  7. \(-100\sqrt{0{,}08}=-100\sqrt{2/25}=-20\sqrt2\).
  8. \(\frac23\sqrt{6\frac34}=\frac23\sqrt{27/4}=\frac23\cdot\frac{3\sqrt3}{2}=\sqrt3\).

Ответ: 1) 6√2; 2) 4√5; 3) 10√3; 4) 7√2/10; 5) √11; 6) −12√3; 7) −20√2; 8) √3.