\[\left( 6\sqrt{2} - 3\sqrt{50} + \sqrt{72} \right) \cdot \sqrt{2} =\]
\[= \left( 6\sqrt{2} - 3 \cdot 5\sqrt{2} + 6\sqrt{2} \right) \cdot \sqrt{2} =\]
\[= \left( 6\sqrt{2} - 15\sqrt{2} + 6\sqrt{2} \right) \cdot \sqrt{2} =\]
\[= - 3\sqrt{2} \cdot \sqrt{2} = - 3 \cdot 2 = - 6\]