﹣3﹙a³-a²+2a-1﹚-2﹙﹣3a³+2a²-1/2a+2﹚-3(﹣a³-a²+2a+1﹚
=-3a³+3a²-6a+3+6a³-4a²+a-4+3a³+3a²-6a-3
=6a³+2a²-11a-4
=6×(-2)³+2×(-2)²-11×(-2)-4
=-48+8+22-4
=-32
﹣3﹙a³-a²+2a-1﹚-2﹙﹣3a³+2a²-1/2a+2﹚-3(﹣a³-a²+2a+1﹚
=-3a³+3a²-6a+3+6a³-4a²+a-4+3a³+3a²-6a-3
=6a³+2a²-11a-4
=6×(-2)³+2×(-2)²-11×(-2)-4
=-48+8+22-4
=-32