This paper is concerned with the existence and multiplicity of positive solutions for the following problem:
where Ω is a smooth bounded domain in with and the parameters . The weight functions , satisfy the following conditions:
() and , where ;
() there exist positive constants and such that and in ;
() and ;
() and for all ;
() there exists such that as .
In (1), if we replace
, it reduces to the following Dirichlet problem of Kirchhoff type:
Problem (2) is related to the stationary analogue of the equation
proposed by Kirchhoff in  as an extension of the classical d’Alembert wave equation for free vibrations of elastic strings. Kirchhoff’s model takes into account the changes in the length of the string produced by transverse vibrations. It received great attention only after Lions  proposed an abstract framework for the problem. The solvability of the Kirchhoff type problem (2) has been paid much attention to by various authors. The positive solutions of such a problem are obtained by using variational methods [3–5]. Perera and Zhang  obtained a nontrivial solution of problem (2) via the Yang index and the critical group. He and Zou  obtained infinitely many solutions by using the local minimum methods and the fountain theorems. Recently, when is a continuous superlinear nonlinearity with critical growth, the existence of positive solutions of the Kirchhoff type problem has been studied [8–13]. Moreover, the paper  considered problem (2) with concave and convex nonlinearities by using a Nehari manifold and fibering map methods, and one obtained the existence of multiple positive solutions. In addition, the corresponding results of the Kirchhoff type problem can be found in [15–25], and the references therein.
In the present paper, we deal with problem (1) and consider the existence and multiplicity of positive solutions of problem (1). About the critical growth situation, the aforementioned papers only showed the existence of positive solutions of the Kirchhoff type problem. Moreover, involving the concave and convex nonlinearities,  only considered the subcritical growth case. Therefore, our purpose is to extend the result of  to critical growth. The main results of this paper extend the corresponding results in  and .
Before stating our results, we give some notations and assumptions. Let , (), . In addition, we denote positive constants by . The main results of this paper are as follows.
Theorem 1 Let , and . Suppose that () and () hold, then there exists such that problem (1) for all has at least one positive solution.
Theorem 2 Let , and . Suppose that (), (), (), () and () hold, then there exists such that problem (1) for all has at least two positive solutions.
Remark 1 Our Theorem 2 extends the results for the critical case of Theorem 1.1 in . Our Theorem 2 shows that we have at least two positive solutions of problem (1), but the authors of the reference only obtain at least one positive solution of problem (1). In addition, the results of Theorem 2.1 in  are extended to critical growth.
This paper is organized as follows. In Section 2, we give the local Palais-Smale condition. The proof of Theorems 1 and 2 is provided in Section 3.