IV-в. Вычислить: 1) \(\frac{0,2}{\sqrt{0,25}}\); 2) \(2\cdot\sqrt{81}\); 3) \(\frac{\sqrt{18}}{\sqrt{32}}\); 4) \(3,6-3\sqrt{0,2}\cdot\sqrt{5}\).

1. \(\frac{0,2}{\sqrt{0,25}}=\frac{0,2}{0,5}=0,4\).
2. \(2\cdot\sqrt{81}=2\cdot9=18\).
3. \(\frac{\sqrt{18}}{\sqrt{32}}=\sqrt{\frac{18}{32}}=\sqrt{\frac{9}{16}}=\frac{3}{4}\).
4. \(3,6-3\sqrt{0,2\cdot5}=3,6-3\sqrt{1}=0,6\).

Ответ: 1) 0,4; 2) 18; 3) \(\frac{3}{4}\); 4) 0,6.