Bilingual edition: English is preserved and Chinese follows each unit. Terminology uses the confirmed v20260916 glossary; automated semantic review remains traceable.
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Integration by Parts

分部积分法

Integration by parts is a useful strategy for simplifying some integrals. It is based on the combination rule for differentiation and the general approach can be summarized by:

分部积分法是一种简化某些积分的有用策略。它基于微分的乘积法则,其一般方法可以概括为:

This technique is particularly appropriate for removing a linear term multiplying an exponential. For example, the integral

这种技术特别适用于消除指数函数前的线性项。例如,积分

can be simplified by the identification

可以通过识别来简化

Then u can be differentiated and dv can be integrated.

然后可以对 u 进行求导,对 dv 进行积分。

The value of the integral is then

积分的值则为
Applications
应用
Average particle energy
平均粒子能量
Mean particle lifetime
平均粒子寿命

If a higher power term of x multiplies the exponential, then the process of integration by parts can be repeated to reduce the power term. Two stages are necessary to integrate a square term.

如果x的高次幂项乘以指数函数,则可以通过分部积分法重复进行,以降低幂次。要积分一个平方项需要两个阶段。
Example:
例:
Hydrogen ground state probability
氢原子基态概率

Three stages are necessary if the integrand has a cubic term, and so on.

如果被积函数中含有三次项,那么需要分三个阶段来处理。

Example:
例:
Radius expectation value, hydrogen atom
氢原子的半径期望值
Index

Integration concepts
索引积分概念
 
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