2. 4√45 − 3√20

Упрощаем корни: \(\sqrt{45}=3\sqrt{5}\), \(\sqrt{20}=2\sqrt{5}\).

\(4\sqrt{45}-3\sqrt{20}=4\cdot3\sqrt{5}-3\cdot2\sqrt{5}=12\sqrt{5}-6\sqrt{5}=6\sqrt{5}\).

Ответ: \(6\sqrt{5}\).