Ответ:

  1. \(\sqrt{9}=3\).
  2. \(7\sqrt{15}\cdot2\sqrt{2}\cdot\sqrt{30}=14\sqrt{900}=14\cdot30=420\).
  3. \(\sqrt{5}\cdot18\cdot\sqrt{10}=18\sqrt{50}=18\cdot5\sqrt{2}=90\sqrt{2}\).
  4. \(\dfrac{\sqrt{15}\cdot\sqrt{12}}{\sqrt{20}}=\sqrt{\dfrac{180}{20}}=\sqrt{9}=3\).
  5. \(\dfrac{(2\sqrt{6})^2}{48}=\dfrac{4\cdot6}{48}=\dfrac{1}{2}\).