|
|
|
|
@ -91,7 +91,8 @@ $$
|
|
|
|
|
$$
|
|
|
|
|
整理后即得所求。
|
|
|
|
|
|
|
|
|
|
---
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
## **辅助函数的构造方法**
|
|
|
|
|
|
|
|
|
|
@ -136,7 +137,7 @@ f'(\xi) + P(\xi)f(\xi) = 0
|
|
|
|
|
$$
|
|
|
|
|
可构造积分因子:
|
|
|
|
|
$$
|
|
|
|
|
\mu(x) = e^{\int P(x)dx}
|
|
|
|
|
\mu(x) = e^{\int P(x)\mathrm{d}x}
|
|
|
|
|
$$
|
|
|
|
|
并设辅助函数:
|
|
|
|
|
$$
|
|
|
|
|
@ -179,7 +180,7 @@ $$
|
|
|
|
|
属于一阶线性微分结构,其中 $P(x) = -2x$。
|
|
|
|
|
积分因子为:
|
|
|
|
|
$$
|
|
|
|
|
\mu(x) = e^{\int (-2x)dx} = e^{-x^2}
|
|
|
|
|
\mu(x) = e^{\int (-2x)\mathrm{d}x} = e^{-x^2}
|
|
|
|
|
$$
|
|
|
|
|
构造辅助函数:
|
|
|
|
|
$$
|
|
|
|
|
@ -219,7 +220,7 @@ f'(\xi) - (1-\xi) f(\xi) = 0
|
|
|
|
|
$$
|
|
|
|
|
积分因子为:
|
|
|
|
|
$$
|
|
|
|
|
\mu(x) = e^{\int (x-1) dx} = e^{\frac{x^2}{2} - x}
|
|
|
|
|
\mu(x) = e^{\int (x-1) \mathrm{d}x} = e^{\frac{x^2}{2} - x}
|
|
|
|
|
$$
|
|
|
|
|
构造辅助函数:
|
|
|
|
|
$$
|
|
|
|
|
|