a) \(\frac{x - 9}{3 + \sqrt{x}} = \frac{(\sqrt{x} - 3)(\sqrt{x} + 3)}{3 + \sqrt{x}} = \sqrt{x} - 3\)
б) \(\frac{16 - 8\sqrt{x} + x}{4 - \sqrt{x}} = \frac{(4 - \sqrt{x})^2}{4 - \sqrt{x}} = 4 - \sqrt{x}\)
в) \(\frac{x + 6\sqrt{x}}{6 + \sqrt{x}} = \frac{\sqrt{x}(\sqrt{x} + 6)}{6 + \sqrt{x}} = \sqrt{x}\)