\[2a \cdot \left( 2a^{2} - 8ab + b^{2} \right) =\]
\[= 2a \cdot 2a^{2} - 2a \cdot 8ab + 2a \cdot b^{2} =\]
\[= 4a^{3} - 16a^{2}b + 2ab^{2}.\]