I'm teaching myself matrices because it could prove useful in the future.

I'll just run through a few things I've done to check if I'm correct:

i'm confident in adding/subtracting and multiplying.

What I'm having trouble getting my mind around is identities, inverses and determinants for 2x2 matrices.

In my book it says that for matrices of a given dimension (2x2) a identityIexists...

$\displaystyle \left(\begin{array}{cc}1&0\\0&1\end{array}\right)$

What does thisImean?

Then after this it says

If $\displaystyle A =\left(\begin{array}{cc}2&3\\1&4\end{array}\right) , AI = IA = A $

I have no idea in the world what this means. Could someone clarify it for me please =]

Thanks in advanced!