Ты просишь упростить выражения под номерами 1, 2, 3, 4, 5 и 6

Конечно, давай упростим выражения! 1) $7\sqrt{28} - \sqrt{80} - 2\sqrt{63} + 3\sqrt{45} = 7\sqrt{4 \cdot 7} - \sqrt{16 \cdot 5} - 2\sqrt{9 \cdot 7} + 3\sqrt{9 \cdot 5} = 7 \cdot 2\sqrt{7} - 4\sqrt{5} - 2 \cdot 3\sqrt{7} + 3 \cdot 3\sqrt{5} = 14\sqrt{7} - 4\sqrt{5} - 6\sqrt{7} + 9\sqrt{5} = (14 - 6)\sqrt{7} + (9 - 4)\sqrt{5} = 8\sqrt{7} + 5\sqrt{5}$ 2) $2\sqrt{\frac{1}{6}} - \sqrt{\frac{2}{3}} + 3\sqrt{\frac{1}{15}} + 4\sqrt{\frac{3}{5}} = 2\frac{\sqrt{1}}{\sqrt{6}} - \frac{\sqrt{2}}{\sqrt{3}} + 3\frac{\sqrt{1}}{\sqrt{15}} + 4\frac{\sqrt{3}}{\sqrt{5}} = \frac{2}{\sqrt{6}} - \frac{\sqrt{2}}{\sqrt{3}} + \frac{3}{\sqrt{15}} + \frac{4\sqrt{3}}{\sqrt{5}} = \frac{2\sqrt{6}}{6} - \frac{\sqrt{2}\sqrt{3}}{3} + \frac{3\sqrt{15}}{15} + \frac{4\sqrt{3}\sqrt{5}}{5} = \frac{\sqrt{6}}{3} - \frac{\sqrt{6}}{3} + \frac{\sqrt{15}}{5} + \frac{4\sqrt{15}}{5} = \frac{5\sqrt{15}}{5} = \sqrt{15}$ 3) $(\sqrt{18} - 3\sqrt{2})^2 = (\sqrt{9 \cdot 2} - 3\sqrt{2})^2 = (3\sqrt{2} - 3\sqrt{2})^2 = 0^2 = 0$ 4) $(1 - \sqrt{3})^2 (1 + \sqrt{3}) = (1 - 2\sqrt{3} + 3)(1 + \sqrt{3}) = (4 - 2\sqrt{3})(1 + \sqrt{3}) = 4 + 4\sqrt{3} - 2\sqrt{3} - 2 \cdot 3 = 4 + 2\sqrt{3} - 6 = -2 + 2\sqrt{3}$ 5) $\frac{3}{\sqrt{5} - \sqrt{6}} - \frac{4}{\sqrt{5} + \sqrt{6}} = \frac{3(\sqrt{5} + \sqrt{6})}{(\sqrt{5} - \sqrt{6})(\sqrt{5} + \sqrt{6})} - \frac{4(\sqrt{5} - \sqrt{6})}{(\sqrt{5} + \sqrt{6})(\sqrt{5} - \sqrt{6})} = \frac{3\sqrt{5} + 3\sqrt{6}}{5 - 6} - \frac{4\sqrt{5} - 4\sqrt{6}}{5 - 6} = \frac{3\sqrt{5} + 3\sqrt{6}}{-1} - \frac{4\sqrt{5} - 4\sqrt{6}}{-1} = -3\sqrt{5} - 3\sqrt{6} + 4\sqrt{5} - 4\sqrt{6} = \sqrt{5} - 7\sqrt{6}$ 6) $\frac{2}{1 + \sqrt{3}} + \frac{3}{3 - \sqrt{5}} = \frac{2(1 - \sqrt{3})}{(1 + \sqrt{3})(1 - \sqrt{3})} + \frac{3(3 + \sqrt{5})}{(3 - \sqrt{5})(3 + \sqrt{5})} = \frac{2 - 2\sqrt{3}}{1 - 3} + \frac{9 + 3\sqrt{5}}{9 - 5} = \frac{2 - 2\sqrt{3}}{-2} + \frac{9 + 3\sqrt{5}}{4} = -1 + \sqrt{3} + \frac{9}{4} + \frac{3\sqrt{5}}{4} = \frac{5}{4} + \sqrt{3} + \frac{3\sqrt{5}}{4}$