In this paper, we look for the weight functions (say g) that admit the following generalized Hardy-Rellich type inequality:
\int_\Omega g (x)u^2 dx \les C\int_\Omega \vert \Delta u \vert ^2 dx,\quad \forall u\in {\rm {\cal D}}_0^{2,2} (\Omega ),
for some constant
C > 0, where
Ω is an open set in ℝ
N with
N ⩾ 1. We find various classes of such weight functions, depending on the dimension
N and the geometry of Ω. Firstly, we use the Muckenhoupt condition for the one-dimensional weighted Hardy inequalities and a symmetrization inequality to obtain admissible weights in certain Lorentz-Zygmund spaces. Secondly, using the fundamental theorem of integration we obtain the weight functions in certain weighted Lebesgue spaces. As a consequence of our results, we obtain simple proofs for the embeddings of
{\cal D}_0^{2,2} into certain Lorentz-Zygmund spaces proved by Hansson and later by Brezis and Wainger.