\[2a^{2};\ \ \ a = \sqrt{3} - 1:\]
\[2 \cdot \left( \sqrt{3} - 1 \right)^{2} =\]
\[= 2 \cdot \left( 3 - 2\sqrt{3} + 1 \right) =\]
\[= 6 - 4\sqrt{3} + 2 = 8 - 4\sqrt{3}.\]