6) \( I = \left( \frac{1}{\sqrt{3}-2} - \frac{1}{\sqrt{3}+2} \right) \frac{2-\sqrt{2}}{1-\sqrt{2}} \) 7) \( \sqrt{5 - \sqrt{3}} \sqrt{2} \sqrt{4 - \sqrt{15}} \) 8) \( \sqrt{15} + \sqrt{60} + \sqrt{84} + \sqrt{140} \) 9) \( \sqrt[3]{26 + 15 \sqrt{3}} + \sqrt[3]{26 - 15 \sqrt{3}} \) 10) \( \frac{5 + \sqrt{5}}{5 - \sqrt{5}} - \frac{5 - \sqrt{5}}{5 + \sqrt{5}} \) 11) \( S = \left( \frac{1}{4 - 2 \sqrt{3}} + \frac{3}{4 + 2 \sqrt{3}} \right) (4 - \sqrt{3}) \) 12) \( V = \sqrt{4 + \sqrt{5} \sqrt{3} + 5 \sqrt{48 - 10 \sqrt{7 + 4 \sqrt{3}}}} \)

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6) \( I = \left( \frac{1}{\sqrt{3}-2} - \frac{1}{\sqrt{3}+2} \right) \frac{2-\sqrt{2}}{1-\sqrt{2}} \)

7) \( \sqrt{5 - \sqrt{3}} \sqrt{2} \sqrt{4 - \sqrt{15}} \)

8) \( \sqrt{15} + \sqrt{60} + \sqrt{84} + \sqrt{140} \)

9) \( \sqrt[3]{26 + 15 \sqrt{3}} + \sqrt[3]{26 - 15 \sqrt{3}} \)

10) \( \frac{5 + \sqrt{5}}{5 - \sqrt{5}} - \frac{5 - \sqrt{5}}{5 + \sqrt{5}} \)

11) \( S = \left( \frac{1}{4 - 2 \sqrt{3}} + \frac{3}{4 + 2 \sqrt{3}} \right) (4 - \sqrt{3}) \)

12) \( V = \sqrt{4 + \sqrt{5} \sqrt{3} + 5 \sqrt{48 - 10 \sqrt{7 + 4 \sqrt{3}}}} \)