13.2 Finding inverses using minors

Note: if you are required to find an inverse using GE in this class, do not use any minors, even on $2\times2$ matrices.

Note: If a matrix is orthonormal, its inverse must be found using a transpose in this class.

In this class, if you need to find an inverse matrix using the method of minors,

• Write the transpose matrix.
• Form a matrix of the minors of each of the elements of the transpose matrix, with a checkerboard sign pattern. (Positive on the main diagonal.)
• Divide by the determinant.
• Evaluate.