I've A^-1 = - A What is A I've figured that A^2= -I but what's then?
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Originally Posted by ahmedzoro10 I've A^-1 = - A What is A I've figured that A^2= -I but what's then? , where .
Originally Posted by alexmahone , where . Not necessarily. There can be many matrices whose square is –I. For 2x2 matrices, you can for example take
How did you get this one?
Originally Posted by ahmedzoro10 How did you get this one? Just note that (there are others as well) and .
Originally Posted by Opalg Not necessarily. There can be many matrices whose square is –I. For 2x2 matrices, you can for example take So how many solutions does a matrix equation like have? (where and are n by n matrices.)
Last edited by alexmahone; January 14th 2012 at 03:41 PM.
Let . Then . So we must have , , , and . You might try things like taking b (or c) equal to 0 or not equal to 0 and see what you get.
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