If A and B are invertible square matrices of the same order, then which of the following is not correct?

1. |AB^-1|=|A|/|B|
2. |(AB)^-1|=1/|A||B|
3. (AB)^-1=B^-1A^-1
4. (A+B)^-1=B^-1+A^-1

Solution