a) \(3\sqrt{28} = 3\sqrt{4\cdot7} = 3\cdot2\sqrt{7} = 6\sqrt{7}\)
б) \(\frac{1}{2}\sqrt{80} = \frac{1}{2}\sqrt{16\cdot5} = \frac{1}{2}\cdot4\sqrt{5} = 2\sqrt{5}\)
в) \(\frac{\sqrt{500}}{5} = \frac{\sqrt{100\cdot5}}{5} = \frac{10\sqrt{5}}{5} = 2\sqrt{5}\)