Existence of solutions for perturbed fourth order elliptic equations with variable exponents

Using variational methods, we study the existence and multiplicity of solutions for a class of fourth order elliptic equations of the form 2 p(x) u − M �R 1 p(x) |∇u| p(x) dx� ∆p(x)u = f(x, u) in Ω, u = ∆u = 0 on ∂Ω, where Ω ⊂ RN, N ≥ 3, is a smooth bounded domain, ∆ 2 p(x) u = ∆(|∆u| p(x)−2∆u) is the operator of fourth order called the p(x)-biharmonic operator, ∆p(x)u = div |∇u| p(x)−2∇u is the p(x)-Laplacian, p : Ω → R is a log-Hölder continuous function, M : [0, +∞) → R and f : Ω × R → R are two continuous functions satisfying some certain condition