Вычислим

1. a) $$2,5\sqrt{3,24} - \frac{1}{2}\sqrt{225} = 2,5 \cdot 1,8 - \frac{1}{2} \cdot 15 = 4,5 - 7,5 = -3$$
2. б) $$1 - 2\sqrt{2\frac{7}{9}} = 1 - 2\sqrt{\frac{25}{9}} = 1 - 2 \cdot \frac{5}{3} = 1 - \frac{10}{3} = \frac{3}{3} - \frac{10}{3} = -\frac{7}{3} = -2\frac{1}{3}$$
3. в) $$(5\sqrt{2} - \sqrt{18}) \cdot \sqrt{2} = (5\sqrt{2} - \sqrt{9 \cdot 2}) \cdot \sqrt{2} = (5\sqrt{2} - 3\sqrt{2}) \cdot \sqrt{2} = 2\sqrt{2} \cdot \sqrt{2} = 2 \cdot 2 = 4$$
4. г) $$(1 - \sqrt{2})^2 \cdot (2\sqrt{2} + 3) = (1 - 2\sqrt{2} + 2) \cdot (2\sqrt{2} + 3) = (3 - 2\sqrt{2}) \cdot (2\sqrt{2} + 3) = 6\sqrt{2} + 9 - 8 - 6\sqrt{2} = 1$$

Ответ:

1. a) $$-3$$
2. б) $$-2\frac{1}{3}$$
3. в) $$4$$
4. г) $$1$$