Compute ABABAB where A=(12)A = \begin{pmatrix} 1 & 2 \end{pmatrix}A=(12) and B=(34)B = \begin{pmatrix} 3 \\ 4 \end{pmatrix}B=(34).
(38)\begin{pmatrix} 3 & 8 \end{pmatrix}(38)
111111
(3468)\begin{pmatrix} 3 & 4 \\ 6 & 8 \end{pmatrix}(3648)
(12)\begin{pmatrix} 1 \\ 2 \end{pmatrix}(12)