1. Let A, B be 3 X 3-matrices. If AB = 0 then A = 0 or B = 0. O True O False 2. If A- and B- both exist and A-1 B-1 = B-A-1, then AB = BA. O True O False 3. If A, B, C are matrices of the same size, then their product ABC is invertible. O True O False 4. Let A, B, C be 2 X 2-matrices. If A is invertible and AB = AC, then B = C. O True O False