The Three Nontrivial Solutions For Two Nonlinear Fourth-order Systems Of Elliptic Equations

This paper is devoted to dealing with the existence of the three nontrivial solutions for two nonlinear fourth-order systems of elliptic equations.The nonlin-ear forms satisfy suplinear and subcritical conditions.First,we use the General minimax principle to obtain the existence of nontrivial solution of nonlinear fourth-order elliptic equation with Navier boundary condition.Second,we use the linking theorem of product space and Nehari manifold to verified the existence of the third nontrivial solution.