\[\left( 3 - \sqrt{2} \right)^{2} =\]
\[= 3^{2} - 2 \cdot 3 \cdot \sqrt{2} - \left( \sqrt{2} \right)^{2} =\]
\[= 9 - 6\sqrt{2} + 2 = 11 - 6\sqrt{2}.\]