2. Вычислите: а) \(\sqrt{121}\cdot0,36\); б) \(\frac{\sqrt{125}}{\sqrt5}\); в) \(3\sqrt{20}-\sqrt{45}+3\sqrt{18}+\sqrt{72}-\sqrt{80}\).

а) \(\sqrt{121}\cdot0.36=11\cdot0.36=3.96\).

б) \(\frac{\sqrt{125}}{\sqrt5}=\sqrt{\frac{125}{5}}=\sqrt{25}=5\).

в)

\(3\sqrt{20}-\sqrt{45}+3\sqrt{18}+\sqrt{72}-\sqrt{80}=\)

\(=3\cdot2\sqrt5-3\sqrt5+3\cdot3\sqrt2+6\sqrt2-4\sqrt5=\)

\(=(6-3-4)\sqrt5+(9+6)\sqrt2=15\sqrt2-\sqrt5\).

Ответ: а) \(3.96\); б) \(5\); в) \(15\sqrt2-\sqrt5\).