3. Вычислите \(\sqrt{3}\cdot(\sqrt{27}-\sqrt{12})\).

Упростим корни: \(\sqrt{27}=3\sqrt{3}\), \(\sqrt{12}=2\sqrt{3}\).

\[\sqrt{3}(\sqrt{27}-\sqrt{12})=\sqrt{3}(3\sqrt{3}-2\sqrt{3})=\sqrt{3}\cdot\sqrt{3}=3.\]

Ответ: \(3\).