\[- 5a^{4} + a^{3}\ при\ a = - 2:\]
\[- 5a^{4} + a^{3} = a^{3}( - 5a + 1) =\]
\[= \left( - 2^{3} \right) \cdot \left( - 5 \cdot ( - 2) + 1 \right) =\]
\[= - 8 \cdot 11 = - 88.\]