I am studying for finals and am looking over previous problems that I missed significant points on. My instructor doesn't comment on why things are incorrect and he doesn't discuss homework, so I am on my own to figure out why I am wrong. Anyway, I would like some help figuring out where I went wrong.
If matrices such that , then are invertible. Furthermore, we have
Show that if then
By the theorem above we have
Which doesn't seem to get me anywhere. Any help is appreciated. Thank you in advance.