Internal
problem
ID
[8929]
Book
:
Own
collection
of
miscellaneous
problems
Section
:
section
4.0
Problem
number
:
37
Date
solved
:
Sunday, March 30, 2025 at 01:55:35 PM
CAS
classification
:
[[_2nd_order, _with_linear_symmetries]]
Solve
Using series expansion around
The type of the expansion point is first determined. This is done on the homogeneous part of the ODE.
The following is summary of singularities for the above ode. Writing the ode as
Where
Combining everything together gives the following summary of singularities for the ode as
Regular singular points :
Irregular singular points :
Since
Let the solution be represented as Frobenius power series of the form
Then
Substituting the above back into the ode gives
Which simplifies to
The next step is to make all powers of
Substituting all the above in Eq (2A) gives the following equation where now all powers of
The indicial equation is obtained from
When
Or
Since
Since the above is true for all
Solving for
Since
Solving for
Since the root of the indicial equation is repeated, then we can construct two linearly independent solutions. The first solution has the form
Now the second solution
Then the general solution will be
In Eq (1B) the sum starts from 1 and not zero. In Eq (1A),
We start by finding the first solution
For
Solving for
Which for the root
At this point, it is a good idea to keep track of
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For
Which for the root
And the table now becomes
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For
Which for the root
And the table now becomes
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For
Which for the root
And the table now becomes
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For
Which for the root
And the table now becomes
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Using the above table, then the first solution
Now the second solution is found. The second solution is given by
Where
And the above is then evaluated at
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N/A since |
N/A |
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The above table gives all values of
Therefore the homogeneous solution is
Hence the final solution is
Order:=6; ode:=x^2*(x^2-2*x+1)*diff(diff(y(x),x),x)-(3+x)*x*diff(y(x),x)+(x+4)*y(x) = 0; dsolve(ode,y(x),type='series',x=0);
Maple trace
Methods for second order ODEs: --- Trying classification methods --- trying a quadrature checking if the LODE has constant coefficients checking if the LODE is of Euler type trying a symmetry of the form [xi=0, eta=F(x)] checking if the LODE is missing y -> Trying a Liouvillian solution using Kovacics algorithm A Liouvillian solution exists Reducible group (found an exponential solution) Group is reducible, not completely reducible <- Kovacics algorithm successful
Maple step by step
ode=x^2*(1-2*x+x^2)*D[y[x],{x,2}] -x*(3+x)*D[y[x],x]+(4+x)*y[x] == 0; ic={}; AsymptoticDSolveValue[{ode,ic},y[x],{x,0,5}]
from sympy import * x = symbols("x") y = Function("y") ode = Eq(x**2*(x**2 - 2*x + 1)*Derivative(y(x), (x, 2)) - x*(x + 3)*Derivative(y(x), x) + (x + 4)*y(x),0) ics = {} dsolve(ode,func=y(x),ics=ics,hint="2nd_power_series_regular",x0=0,n=6)