题目

We know that many animals do not stay in one place. Birds, fish and other animals move from one place to another at a certain time. They move for different reasons most of them move to find food more easily, but others move to get away from places that are too crowded. When cold weather comes, many birds move to warmer places to find food. Some fishes give birth in warm water and move to cold water to feed. The most famous migration（迁移）is probably the migration of the fish, which is called “salmon”. This fish is born in fresh water but it travels many miles to salt water. There it 20．计算不定积分${∫}_{\;}^{\;}$$\frac{{x}^{3}+3{x}^{2}sinx+2x-1}{{x}^{2}}$dx．