1. The problem statement, all variables and given/known data Determine which of the formulas hold for all invertible nxn matrices A and B 1. (In-A)(In+A) = In - A^2 2. (A+B)(A-B) = A^2 - B^2 3. A^8*B^5 is invertible 4. (A+A^-1)^9 = A^9 + A^-9 5. AB = BA 6. A+A^-1 is invertible I know 5 is right, and number 2 wrong, but what else?