Another Group theory question - sorry! Any help greatly appreciated...
you already have $\displaystyle A$ and $\displaystyle B$ initial elements..
now, how will you get other elements? try solving for $\displaystyle AB$, $\displaystyle BA$, $\displaystyle AA$, $\displaystyle BB$..
if you obtain other elements other than the identity, $\displaystyle A$ and $\displaystyle B$, try multiplying it with either $\displaystyle A$ or $\displaystyle B$ to obtain another elements..