Past exam of the mathematics course of the University of Cambridge / 2010 / ii / Paper 4 / 37A / ii

The $C$ term produces a nondecaying velocity at infinity and the $D$ term a growing one, so decay forces $C=D=0$. The first two boundary equations become $A+B=1/2$ and $-A+B=0$, givingThe remaining velocity terms decay respectively as $R^{-3}$ and $R^{-1}$.