# Matricies

• August 19th 2009, 03:34 AM
manalive04
Matricies
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 $(AB)^{-1} = B^{-1} A^{-1}$
• August 19th 2009, 03:53 AM
mr fantastic
Quote:

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?
• August 19th 2009, 04:09 AM
manalive04
matricies
Quote:

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
• August 19th 2009, 04:25 AM
mr fantastic
Quote:

Originally Posted by manalive04
please explain this further i dont understand - sorry

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