本文试应用求解一阶线性微分方程的方法导出几类常见的函数项级数的求和公式。
The sum formulas of several kinds of ordinary series with function term are deduced by using the method of solving linear differential equation.
可分离变量的一阶微分方程是一类特殊的一阶微分方程，它在实际中有着广泛的用途。
Separable variables are a special class of first order differential equations, which has a wide range of USES in practice.
用泛函的方法研究一类二阶微分方程周期解的存在性。
We studied a class of two order differential equations by means of the functional method.
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