9.
[tex]b) \ \frac{\sqrt{75}-\sqrt{27}}{\sqrt{3}} = \frac{\sqrt{25\cdot3}-\sqrt{9\cdot3}}{\sqrt{3}}=\frac{\sqrt{25}\cdot\sqrt{3}-\sqrt{9}\cdot\sqrt{3}}{\sqrt{3}} = \frac{5\sqrt{3}-3\sqrt{3}}{\sqrt{3}} = \frac{2\sqrt{3}}{\sqrt{3}} = 2\\\\c) \ \sqrt[3]{250}+\sqrt[3]{-54} = \sqrt[3]{125\cdot2}-\sqrt[3]{27\cdot2} = \sqrt[3]{125}\cdot\sqrt[3]{2}-\sqrt[3]{27}\cdot\sqrt[3]{2} =\\\\= 5\sqrt[3]{2}-3\sqrt[3]{2} = 2\sqrt[3]{2}[/tex]
