Răspuns:
[tex]x = 5\sqrt{7} \\y = 2\sqrt{7} \\a) x^{-1} = \frac{1}{5\sqrt{7}} = \frac{\sqrt{7} }{35} \\b) x + y = 5\sqrt{7} + 2\sqrt{7} = 7\sqrt{7}\\c) y - x = 2\sqrt{7} - 5\sqrt{7} = -3\sqrt{7}\\d) y^{2} = (2\sqrt{7})^{2} = 2^{2}*(\sqrt{7} )^{2} = 4 * 7 = 28[/tex]
