Ответ:

  1. \(\sqrt{16}=4\).
  2. \(\sqrt{121}=11\).
  3. \(\sqrt{324}=18\).
  4. \(\sqrt{1600}=40\).
  5. \(\sqrt{50}=5\sqrt2\).
  6. \(\sqrt{28}=2\sqrt7\).
  7. \(\sqrt{0.64}=0.8\).
  8. \(\sqrt2\cdot\sqrt2=2\).
  9. \(\sqrt{18}\cdot\sqrt2=\sqrt{36}=6\).
  10. \(\sqrt{0.4}=\sqrt{4/10}=\sqrt{10}/5\).
  11. \((\sqrt5)^2=5\).
  12. \((4\sqrt7)^2=16\cdot7=112\).
  13. \(\sqrt{90}=3\sqrt{10}\).
  14. \(\sqrt{25-9}=\sqrt{16}=4\).
  15. \(\sqrt{25\cdot9}=\sqrt{225}=15\).
  16. \(\sqrt{10^2-8^2}=\sqrt{100-64}=\sqrt{36}=6\).
  17. \((\sqrt5)^3=5\sqrt5\).
  18. \(6/\sqrt2=3\sqrt2\).
  19. Так как \(\sqrt4=2\), \((\sqrt3+\sqrt4)(\sqrt3-\sqrt4)=3-4=-1\).
  20. \((\sqrt5-3)^2=5-6\sqrt5+9=14-6\sqrt5\).