\[(3a - a)^{2} - a^{2}(a - 2)(a + 2) + 2a\left( 7 + 3a^{2} \right) =\]
\[= 9a^{2} - 6a^{3} + a^{4} - a^{2}\left( a^{2} - 4 \right) + 14a + 6a^{3} =\]
\[= 9a^{2} + a^{4} + 14a - \ a^{4} + 4a^{2} =\]
\[= 13a^{2} + 14a\]