$a_{11}C_{11} + a_{12}C_{12} + a_{13}C_{13}$

$a_{11}C_{11} - a_{12}C_{12} + a_{13}C_{13}$

$a_{11}C_{21} + a_{12}C_{22} + a_{13}C_{23}$

$a_{11}a_{22}a_{33}$