SOLVED: THEOREM 6 If A is an invertible matrix, then A-1 is invertible and (A-I)-I = A If A and B are n X n invertible matrices, then S0 is AB, and
Suppose [math]A,B[/math] are [math]n\times n[/math] matrices such that [math]AB[/math] is invertible and [math]B[/math] is invertible. How do you prove that [math]A[/math] is invertible? - Quora