- 100

- 0

w'' + (1/(1+z^2)) w = 0.

The term 1/(1+z^2) I recognize as a geometric series and can be expressed as sum of 0 to infinity of: (-z^2)^n.

But I'm having trouble multiplying it with w, which is also a power series. And also what is the radius of convergence for general initial conditions?

Thanks.