Ответ:
- \((\sqrt{3}\cdot\sqrt{7})^2-1=(\sqrt{21})^2-1=21-1=20\).
- \(\sqrt{9}+\left(\sqrt{0.9}\right)^2=3+0.9=3.9\).
- \(\sqrt{2.4}\cdot\sqrt{60}=\sqrt{2.4\cdot60}=\sqrt{144}=12\).
- \(\frac{3}{5}\sqrt{50}\cdot\sqrt{8}=\frac{3}{5}\sqrt{400}=\frac{3}{5}\cdot20=12\).
