\[2a^{3}\left( 5a^{2} + a - 6 \right) - 10a^{5} =\]
\[= 2a^{4} - 12a³\]
\[при\ a = - 2:\]
\[2 \cdot 16 + 12 \cdot 8 = 32 + 96 = 128.\]