Question

If det(A)=-7
A= | a b c |
| d e f |
| g h i |

Find det(2A^-1), det((2A)^-1).
Find
| a g d |
| b h e |
| c i f |

Answer 1

As you can see from your own post, it is very difficult to type and show matirices and determinants in this format.

Take a look at these sites, thy summarize most of the important properties very nicely.

http://www.sosmath.com/matrix/determ0/determ0.html

http://www.ping.be/~ping1339/determ.htm