1.2.3 The Series Solution Method
For differential equations of any order, with constant coefficients or with
variable coefficients, with x = 0 is an ordinary point, we can use the series
solution method to determine the series solution of the differential equation.
The obtained series solution may converge the exact solution if such a closed
form solution exists. If an exact solution is not obtainable, we may use a
truncated number of terms of the obtained series for numerical purposes.
Although the series solution can be used for equations with constant coeffi-
cients or with variable coefficients, where x = 0 is an ordinary point, but this
method is commonly used for ordinary differential equations with variable
coefficients where x = 0 is an ordinary point.
The series solution method assumes that the solution near an ordinary
point x = 0 is given by