By the co factor of an element of a matrix we mean the product of (-1)^{i+j }and the minor of the concerned element (M_{ij})

Where C_{ij }= the co factor of the element in the ith row and jth column of the matrix.

(-1)^{i+j }=the factor determining the algebraic sign depending upon the number of row (i) and number of column (j) in which the element occurs in the matrix.

M_{ij }= the minor of the element in the ith row and *j*th column of the matrix.

Thus, C_{11} = (-1)^{1+1}, m_{11}; c_{12} = (-1)^{1+2}. M_{12}, and c_{13} = (-1)^{1+3}. M_{13}

**Minor **

By the minor of an element of a matrix we mean the sub square-matrix of the given matrix along which the particular element (e_{ij}) does not exist. It is obtained by deleting the row and the column on which the particular element (e_{ij}) lies. It is representing by M_{ij}, which denotes the minor of an element in the ith row and jth column of the matrix. Its value is obtained by deducting the product of its non-leading diagonal elements from the product of its leading diagonal elements.

**Examples:**