If $$A = \left[ {\matrix{ 1 & 1 & { - 1} \cr 2 & { - 3} & 4 \cr 3 & { - 2} & 3 \cr } } \right]$$ and $$B = \left[ {\matrix{ { - 1} & { - 2} & { - 1} \cr 6 & {12} & 6 \cr 5 & {10} & 5 \cr } } \right]$$, then which of the following is/are correct?

1. A and B commute.

2. AB is a null matrix.

Select the correct answer using the codes given below.

Which one of the following matrices is an elementary matrix?

If $$A = \left[ {\matrix{ 2 & 7 \cr 1 & 5 \cr } } \right]$$, then what is $$A + 3{A^{ - 1}}$$ equal to?

where, I is the identity matrix of order 2.

The matrix $$\left[ {\matrix{ 0 & { - 4 + i} \cr {4 + i} & 0 \cr } } \right]$$ is