Posted by **katy** on Wednesday, December 16, 2009 at 8:30pm.

Why is (AB)^-1 = B^-1A^-1 in matrices, and not (AB)^-1 = A^-1B^-1

- math -
**Marth**, Wednesday, December 16, 2009 at 9:13pm
let A be an m by n matrix and B be a n by p matrix. Then A*B is defined. Also, A^-1 is an n by m matrix, and B^-1 is an p by n matrix. So B^-1 * A^-1 is also defined, but A^-1 * B^-1 may not be.

Or, in other words, the commutative property of scalar multiplication does not apply to matrices.

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