4. Упростите выражение: a) \(35\sqrt{2} + 23\sqrt{27} - \sqrt{98}\); 6) \((4\sqrt{3} + \sqrt{27})\sqrt{3}\); в) \((\sqrt{5} - \sqrt{3})^2\).

a) \(35\sqrt{2} + 23\sqrt{27} - \sqrt{98} = 35\sqrt{2} + 23\sqrt{9 \cdot 3} - \sqrt{49 \cdot 2} = 35\sqrt{2} + 23 \cdot 3\sqrt{3} - 7\sqrt{2} = 35\sqrt{2} + 69\sqrt{3} - 7\sqrt{2} = 28\sqrt{2} + 69\sqrt{3}\)

б) \((4\sqrt{3} + \sqrt{27})\sqrt{3} = (4\sqrt{3} + \sqrt{9 \cdot 3})\sqrt{3} = (4\sqrt{3} + 3\sqrt{3})\sqrt{3} = 7\sqrt{3}\sqrt{3} = 7 \cdot 3 = 21\)

в) \((\sqrt{5} - \sqrt{3})^2 = (\sqrt{5})^2 - 2\sqrt{5}\sqrt{3} + (\sqrt{3})^2 = 5 - 2\sqrt{15} + 3 = 8 - 2\sqrt{15}\)

Ответ: а) \(28\sqrt{2} + 69\sqrt{3}\); б) 21; в) \(8 - 2\sqrt{15}\)