We study the inhomogeneous linearized Korteweg-de Vries (KdV) equation
. It is solved by the inverse scattering transform method. The secular
-producing terms on the right-hand side (rhs) are characterized in sev
eral ways: first we give a mathematical characterization as resonant t
erms. Second, the secular-producing terms are interpreted as conserved
densities of the KdV equation. Third, it is checked that the removal
of all linear terms from the rhs, polynomial in the solution of KdV, e
nsures the boundness of the solution of the linearized equation. Fourt
h, considering this solution itself as the rhs, we determine which par
t of it is secular producing, and which part is not. (C) 1998 American
Institute of Physics. [S0022-2488(98)03006-0].