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

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

$

Would the answer be:

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

$ or $\displaystyle \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?

Thanks in advance

Craig