\[\left( b^{2} + 2b \right)^{2} - b^{2}(b - 1)(b + 1) + 2b\left( 3 - 2b^{2} \right) =\]
\[= b^{4} + 4b^{3} + 4b^{2} - b^{2}\left( b^{2} - 1 \right) + 6b - 4b^{3} =\]
\[= b^{4} + 4b^{2} + 6b - b^{4} + b^{2} = 5b^{2} + 6b\]