Can't do it by Binomial expansion as well.
The question asks to "solve" the following differential equation.
We have not been told yet how to use the Method Of Undetermined Coefficients or by variable coefficients.
We have, however, solved similar questions with partial fractions.
I therefore tried the question in the same way.
After solving I get,
Then after solving (as D is the differential operator) I get the following.
Where as the answer is simply