Hello,How can i solve this problem? I have tried to solve with mathematica but it does not answer correctly Could you kindly help me?
Thank you very much it is correct. Also could you help me on this?
Just use the modified operator D[expr, r, r] + 1/r D[expr, r] - 4/r^2 expr.
D[expr, r, r] + 1/r D[expr, r] - 4/r^2 expr
I think that it is an operator square, not a numeric square:
op[expr_, r_] := D[expr, r, r] + 1/r D[expr, r]; DSolve[op[op[f[r], r], r] == 0, f, r]
