3. Let A be a 2 x 2 matrix with integer entries.
a. Suppose D(A_1, A_2) = +/- 1. Show that A^-1 has all integer entries.
*b. Conversely, suppose A and A^-1 are both matrices with integer entries. Prove that D(A_1, A_2) = +/- 1.
This provides a proof regarding integer entries in a matrix. This solution is attached as a Word document.