Thanks for your help. I have noted all your points. Actually, these equations (Eq.1 and 2) they came from PDE. I used separation of variables method and then equate with the Lambda so it becomes eigenvalue problem. The first equation can be solved but the second one is difficult to solve it is a Sturm-Liouville problem. I want to find the eigenvalue (Lambda) and eigenfunction. So how can I solve it? How can I solve the general solution of the equation?
PDE:
D[\[Theta][x, y], {x, 1}] ==
Subscript[A,
4]/(\[Epsilon]*(Y^2 Subscript[A, 1] + Y*Subscript[A, 2] + Subscript[
A, 3])) D[\[Theta][x, y], {y, 2}]
where A1, A2, A3,\Epsilon
are constants.
Initial Condition
\[Theta] (0, y) == 0
Boundary Condition
\[Theta]' (x, 1) == 0