# Math Help - Inverse of a matrix

1. ## Inverse of a matrix

Hi just a quick question on matrices, when finding the inverse of the matrix:

$\left(\begin{array}{cc}a&b\\c&d\end{array}\right)
$

$\frac{1}{ad-bc} \left(\begin{array}{cc}-a&c\\b&-d\end{array}\right)
$
or $\frac{1}{|ad-bc|} \left(\begin{array}{cc}-a&c\\b&-d\end{array}\right)
$

Completely forgot if you used the modulus of the determinant or not?

Craig

2. Originally Posted by craig
Hi just a quick question on matrices, when finding the inverse of the matrix:

$\left(\begin{array}{cc}a&b\\c&d\end{array}\right)
$

$\frac{1}{ad-bc} \left(\begin{array}{cc}-a&c\\b&-d\end{array}\right)
$
or $\frac{1}{|ad-bc|} \left(\begin{array}{cc}-a&c\\b&-d\end{array}\right)
$

Completely forgot if you used the modulus of the determinant or not?

Craig
Hi Craig,

the matrix inverse is

3. blank

4. Originally Posted by masters
Hi Craig,

the matrix inverse is

Thank you