Matricies

**manalive04** · Aug 19th 2009, 03:34 AM

Show that if A and B are two n x n matricies with inverses $A^{-1}$ and $B^{-1}$ , then AB has an inverse and that $(AB)^{-1} = B^{-1} A^{-1}$

**mr fantastic** · Aug 19th 2009, 03:53 AM

Originally Posted by manalive04

Show that if A and B are two n x n matricies with inverses $A^{-1}$ and $B^{-1}$ , then AB has an inverse and that $(AB)^{-1} = B^{-1} A^{-1}$

Calculate $(AB) (B^{-1} A^{-1})$ and $(B^{-1} A^{-1}) (AB)$ . What do you find?

**manalive04** · Aug 19th 2009, 04:09 AM

Originally Posted by mr fantastic

Calculate $(AB) (B^{-1} A^{-1})$ and $(B^{-1} A^{-1}) (AB)$ . What do you find?

please explain this further i dont understand - sorry

**mr fantastic** · Aug 19th 2009, 04:25 AM

Originally Posted by manalive04

please explain this further i dont understand - sorry

There's nothing further to explain .... Do the matrix multiplications!

Thread: Matricies