Вот подробное решение представленных заданий:
5. \( \sqrt{72} \times \sqrt{2} \)
\[
\sqrt{72} \times \sqrt{2} = \sqrt{72 \cdot 2} = \sqrt{144} = 12.
\]
Ответ: 12.
6. \( \sqrt{3} \times (\sqrt{12} + \sqrt{243}) \)
\[
\sqrt{12} = \sqrt{4 \cdot 3} = 2\sqrt{3}, \quad \sqrt{243} = \sqrt{81 \cdot 3} = 9\sqrt{3}.
\]
\[
\sqrt{3} \times (\sqrt{12} + \sqrt{243}) = \sqrt{3} \times (2\sqrt{3} + 9\sqrt{3}) = \sqrt{3} \times 11\sqrt{3} = 33.
\]
Ответ: 33.
7. \( \frac{\sqrt{48} + \sqrt{108}}{2\sqrt{3}} \)
\[
\sqrt{48} = \sqrt{16 \cdot 3} = 4\sqrt{3}, \quad \sqrt{108} = \sqrt{36 \cdot 3} = 6\sqrt{3}.
\]
\[
\frac{\sqrt{48} + \sqrt{108}}{2\sqrt{3}} = \frac{4\sqrt{3} + 6\sqrt{3}}{2\sqrt{3}} = \frac{10\sqrt{3}}{2\sqrt{3}} = 5.
\]
Ответ: 5.
8. \( 3\sqrt{100} + 4\sqrt{196} \)
\[
\sqrt{100} = 10, \quad \sqrt{196} = 14.
\]
\[
3\sqrt{100} + 4\sqrt{196} = 3 \cdot 10 + 4 \cdot 14 = 30 + 56 = 86.
\]
Ответ: 86.
9. \( (\sqrt{9} + \sqrt{5})(\sqrt{9} - \sqrt{5}) \)
\[
(\sqrt{9} + \sqrt{5})(\sqrt{9} - \sqrt{5}) = \sqrt{9}^2 - \sqrt{5}^2 = 9 - 5 = 4.
\]
Ответ: 4.
10. \( (\sqrt{8} + \sqrt{14})^2 \)
\[
(\sqrt{8} + \sqrt{14})^2 = \sqrt{8}^2 + 2\sqrt{8}\sqrt{14} + \sqrt{14}^2 = 8 + 2\sqrt{112} + 14 = 22 + 4\sqrt{7}.
\]
Ответ: \( 22 + 4\sqrt{7} \).
11. \( \frac{\sqrt{80} + \sqrt{15}}{\sqrt{5}} \)
\[
\sqrt{80} = \sqrt{16 \cdot 5} = 4\sqrt{5}.
\]
\[
\frac{\sqrt{80} + \sqrt{15}}{\sqrt{5}} = \frac{4\sqrt{5} + \sqrt{15}}{\sqrt{5}} = 4 + \frac{\sqrt{15}}{\sqrt{5}} = 4 + \sqrt{3}.
\]
Ответ: \( 4 + \sqrt{3} \).
12. \( \sqrt{6} \cdot x = \sqrt{150} - \sqrt{96} \)
\[
\sqrt{150} = \sqrt{25 \cdot 6} = 5\sqrt{6}, \quad \sqrt{96} = \sqrt{16 \cdot 6} = 4\sqrt{6}.
\]
\[
\sqrt{6} \cdot x = \sqrt{150} - \sqrt{96} = 5\sqrt{6} - 4\sqrt{6} = \sqrt{6}.
\]
\[
\frac{\sqrt{6} \cdot x}{\sqrt{6}} = \frac{\sqrt{6}}{\sqrt{6}}, \quad x = 1.
\]
Ответ: \( x = 1 \).