Answer 1

To multiply, we will use distributive law as follows:

\[\left( a - 1 \right)\left( 0 . 1 a^2 + 3 \right)\]

\[ = 0 . 1 a^2 \left( a - 1 \right) + 3\left( a - 1 \right)\]

\[ = 0 . 1 a^3 - 0 . 1 a^2 + 3a - 3\]

Thus, the answer is \[0 . 1 a^3 - 0 . 1 a^2 + 3a - 3\].