\[- 3a^{3} - 7a^{2} + 5a^{3} - 3a^{2} + 2a =\]
\[= 2a^{3} - 10a^{2} + 2a\]
\[при\ a = - 3:\]
\[- 2 \cdot 27 - 10 \cdot 9 - 2 \cdot 3 =\]
\[= - 54 - 90 - 6 = - 150.\]