Solution

ID: past-exam-of-the-mathematics-course-of-the-university-of-cambridge/2016/ia/paper-2/7a/c/solution

Here the indicial equation has the repeated root . The first Frobenius method solution is . Since , the Abel identity gives . Reduction of order with produces
where the additive constant is absorbed into . In particular the logarithmic coefficient is nonzero: an additional independent real analytic solution does not exist.
The general local form is
This is the repeated-root Logarithmic Frobenius solution. On the negative real side one may use , or use a fixed logarithm branch for a complex solution.

New to topics? Read the docs here!