[header] How to find the inverse of a 3x3 matrix [title] Check the determinant of the matrix. [step] You need to calculate the determinant of the matrix as an initial step. If the determinant is 0, then your work is finished, because the matrix has no inverse. 
The determinant of matrix m can be represented symbolically as det (m). [substeps] For a 3x3 matrix, find the determinant by first to review finding the determinant of a matrix, see find the determinant of a 3x3 matrix.