# inverse matrices

• Dec 19th 2008, 10:36 AM
waterboy
inverse matrices
Show that the following matrices are inverse of each other

1 2
4 6

-3 1
2 -1/2
• Dec 19th 2008, 10:41 AM
masters
Quote:

Originally Posted by waterboy
Show that the following matrices are inverse of each other

1 2
4 6

-3 1
2 -1/2

One must assume that you know how to multiply matrices. If a matrix is the inverse of another matrix then their product will be the identity matrix.

$AB=BA=\left[\begin{array}{cc}1 & 0 \\ 0 & 1 \end {array}\right]$

Multiply them and see what happens.
• Dec 19th 2008, 10:43 AM
Plato
Given $X = \left[ {\begin{array}{rr}
1 & 2 \\
4 & 6 \\

\end{array} } \right]\,\& \,Y = \left[ {\begin{array}{rr}
{ - 3} & 1 \\
2 & { - 1/2} \\ \end{array} } \right]$

You must show that $XY = YX = \left[ {\begin{array}{cc}
1 & 0 \\
0 & 1 \\ \end{array} } \right]$