# determining matrix size

• June 16th 2009, 04:29 PM
chrisc
determining matrix size
Show that if A is an [m x n] matrix and A(BA) is defined, then B is an [n x m] matrix.
• June 16th 2009, 05:07 PM
pickslides
If A has order $m\times n$ look at BA first of all

For be BA to be defined B must have order $k\times m$ in turn BA must have order $k\times n$

Now for A(BA) to be defined $k=n$ therefore B has order $n\times m$
• June 23rd 2009, 02:27 PM
chrisc
thank you, easy to understand when its right in front of me (Hi)