Matrix Questions: Addition, Inverse

Date: 8/6/96 at 21:31:52
From: Anonymous
Subject: Matrix Questions: Addition, Inverse

Hello,

Please tell me how to solve these problems:

 i) (1 2) + (-1 -2) =?

ii) If A = (3 4), is it A inverse?

Date: 8/7/96 at 9:2:54
From: Doctor Anthony
Subject: Re: Matrix Questions: Addition, Inverse

i) (1 2) + (-1 -2) =?

When you add matrices, (or in this case row vectors), you simply add 
the corresponding terms in each matrix.  So

 (1  2) + (-1  -2) = (1-1  2-2) = (0  0) 



ii) If A = (3 4), is it A inverse?

To have an inverse, A must be a square matrix, i.e. the same numbers 
of rows and columns.

-Doctor Anthony,  The Math Forum
 Check out our web site!  http://mathforum.org/dr.math/