Internal
problem
ID
[9137]
Book
:
Second
order
enumerated
odes
Section
:
section
2
Problem
number
:
15
Date
solved
:
Sunday, March 30, 2025 at 02:23:09 PM
CAS
classification
:
[[_2nd_order, _linear, _nonhomogeneous]]
Time used: 0.200 (sec)
Solve
This is second order non-homogeneous ODE. In standard form the ODE is
Where
Where
This is Euler second order ODE. Let the solution be
Simplifying gives
Since
Or
Equation (1) is the characteristic equation. Its roots determine the form of the general solution. Using the quadratic equation the roots are
Since the roots are real and distinct, then the general solution is
Where
Next, we find the particular solution to the ODE
The particular solution
Where
In the Variation of parameters
Where
Which gives
Therefore
Which simplifies to
Which simplifies to
Therefore Eq. (2) becomes
Which simplifies to
Hence
And Eq. (3) becomes
Which simplifies to
Hence
Therefore the particular solution, from equation (1) is
Which simplifies to
Therefore the general solution is
Will add steps showing solving for IC soon.
Summary of solutions found
Time used: 0.188 (sec)
Solve
Writing the ode as
Comparing (1) and (2) shows that
Applying the Liouville transformation on the dependent variable gives
Then (2) becomes
Where
Substituting the values of
Comparing the above to (5) shows that
Therefore eq. (4) becomes
Equation (7) is now solved. After finding
The first step is to determine the case of Kovacic algorithm this ode belongs to. There are 3 cases depending on the order of poles of
Case |
Allowed pole order for |
Allowed value for |
1 |
|
|
2 |
Need to have at least one pole
that is either order |
no condition |
3 |
|
|
The order of
The poles of
Attempting to find a solution using case
Looking at poles of order 2. The partial fractions decomposition of
For the pole at
Since the order of
Since the
The following table summarizes the findings so far for poles and for the order of
pole |
pole order | |
|
|
| | | | |
Order of |
|
|
|
|
| | |
Now that the all
Where
Since
The above gives
Now that
Let
Substituting the above in eq. (1A) gives
The equation is satisfied since both sides are zero. Therefore the first solution to the ode
The first solution to the original ode in
Since
Which simplifies to
The second solution
Since
Therefore the solution is
This is second order nonhomogeneous ODE. Let the solution be
Where
The homogeneous solution is found using the Kovacic algorithm which results in
The particular solution
Where
In the Variation of parameters
Where
Which gives
Therefore
Which simplifies to
Which simplifies to
Therefore Eq. (2) becomes
Which simplifies to
Hence
And Eq. (3) becomes
Which simplifies to
Hence
Therefore the particular solution, from equation (1) is
Which simplifies to
Therefore the general solution is
Will add steps showing solving for IC soon.
Summary of solutions found
ode:=diff(diff(y(x),x),x)-2/x^2*y(x) = x*exp(-x^(1/2)); dsolve(ode,y(x), singsol=all);
Maple trace
Methods for second order ODEs: --- Trying classification methods --- trying a quadrature trying high order exact linear fully integrable trying differential order: 2; linear nonhomogeneous with symmetry [0,1] trying a double symmetry of the form [xi=0, eta=F(x)] -> Try solving first the homogeneous part of the ODE checking if the LODE has constant coefficients checking if the LODE is of Euler type <- LODE of Euler type successful <- solving first the homogeneous part of the ODE successful
ode=D[y[x],{x,2}]-2/x^2*y[x] == x*Exp[-x^(1/2)]; ic={}; DSolve[{ode,ic},y[x],x,IncludeSingularSolutions->True]
from sympy import * x = symbols("x") y = Function("y") ode = Eq(-x*exp(-sqrt(x)) + Derivative(y(x), (x, 2)) - 2*y(x)/x**2,0) ics = {} dsolve(ode,func=y(x),ics=ics)