- #1
DeadOriginal
- 274
- 2
Homework Statement
I want to find two linearly independent solutions of
$$
x^{2}y''-2x^{2}y'+(4x-2)y=0.
$$
The Attempt at a Solution
The roots to the indicial polynomial are ##r_{1}=2## and ##r_{2}=-1##.
I found one solution which was ##x^{2}## and I am having trouble finding the second solution.
After all of the arithmetic I came up with the equation
$$
[r(r-1)-2]c_{0}+\sum\limits_{k=1}^{\infty}\left[(k+r)(k+r-1)-2\right]c_{k}x^{k}+4c_{k-1}x^{k}-2c_{k-1}(k+r-1)x^{k}.
$$
I let ##r=-1## so that I get
$$
\left[(k-1)(k-2)-2\right]c_{k}+4c_{k-1}-2c_{k-1}(k-2)=0
$$
and so
$$
c_{k}=\frac{2(k-4)c_{k-1}}{k(k-3)}.
$$
The recurrence relation becomes undefined for k=3 and onwards. How do I deal with this? The solution skips ##c_{3}## and seemingly magically obtains a formula for ##c_{4}## and onwards.