I'm trying to find the homogenous solutions of this equation. I know there are two, but I can only find one.
The Attempt at a Solution
Using the characteristic function:
a2-4a+4=a <=> (a-2)2=0
is a solution. However, since this is a 2nd order differential equation, I should have two. I can solve the rest of the equation if I can find the 2nd solution. I've tought about it a lot but can't manage to find the answer... All help will be appreciated.