Consider the below statements - (i) For a matrix system AX = B, there will be a unique solution only iff |A| ≠ 0. (ii) A
Look at it this way: rule: unique iff |A|≠0. If |A|=0 and (adjA)B=0, you get infinite solutions. So i and iii correct. Full logic.
Ref: NCERT Mathematics Class XII — Matrices and Determinants
