( A= left[ begin array rrr 4 & 1 & 5 -2 & -1 & -3 3 & -4 & -9 end array right], B= left[ begin array ccc a^ 2 & b c & c a+c^ 2 a^ 2 +a b & b^ 2 & c a a b & b^ 2 +b c & c^ 2 end array right] )