Two special classes of symmetric coefficient matrices were defined based on characteristics matrix; meanwhile, the expressions of the solution to inverse problems are given and the conditions for the solvability of these problems are studied relying on researching. Finally, the optimal approximation solution of these problems is provided. 1. Introduction In recent years, a lot of matrix problems have been used widely in the fields of structural design, automatic control, physical, electrical, nonlinear programming and numerical calculation, for example, a matrix Eigen value problem was applied for mixed convection stability analysis in the Darcy media by Serebriiskii et al.  and some of the problems based on the nonskew symmetric orthogonal matrices were studied by Hamed and Bennacer in 2008 , but some of the matrix inverse problems still need further research in order to make it easier to discuss relevant issues. Therefore, in this paper, we studied the inverse problems of two kinds of special matrix equations based on the existing research achievements, moreover, the expressions and conditions of the matrix solutions are given by related matrix-calculation methods. Some definitions and assumptions of the inverse problem for two forms of special matrices are given in Section 2. In Sections 3 and 5 we discuss the existence and expressions of general solution based on the two classes of matrices, and in Sections 4 and 6 we prove the uniqueness of matrices for researching related inverse problems. 2. Definitions and Assumptions of Inverse Problems for Two Forms of Special Matrices In order to research some inverse problems of related matrices, we give the following definitions and assumptions. Definition 1. When , , , , , and , will be called the first-class special symmetric matrix and the set of these special symmetric matrices is denoted by . The corresponding problems are as follows. Problem 1. When , can be obtained, so that . Problem 2. When , can be obtained, so that , where is the solution set of the first problem. Definition 2. When , and , will be called the second-class special symmetric matrix and the set of these special symmetric matrices is denoted by . The corresponding problems are as follows. Problem 1. When , can be found, so that . Problem 2. When , can be found, so that , where is the solution set of the first problem. 3. Existence and Expression of General Solutions Based on the First-Class Special Symmetric Matrix for Problem 1 To research the structure and properties of the special symmetric matrix , first of all, we have the
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