|2A*B^-1|
= 2^n |A*| |B^-1|
= 2^n * 2^(n-1) * (-1/3)
= -2^(2n-1) / 3这里用到几个性质:1. |kA| = k^n |A|2. |AB| = |A||B|3. |A*| = |A|^(n-1)4. |A^-1| = 1/|A|