Firstly, sorry if this is the wrong section...and also sorry for my crap latex skills!

Prove by induction that

$\displaystyle

M^n = \left(\begin{array}{cc}2^n&3(2^n - 1)\\0&1\end{array}\right)

$

Okey so i did

$\displaystyle

M^n . M

$

Where M is

$\displaystyle

M^n = \left(\begin{array}{cc}2&3\\0&1\end{array}\right)

$

Now i get the

$\displaystyle

2^(n+1)

$

bit required for the induction, but how to i get

$\displaystyle

3.3(2^n - 1) + 3(2^n - 1)

$

into the required form?

Thanks in advanced for any help given

Edit: oo the latex worked! Score! lol.