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

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

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