Here, D=∣12213312a2−1∣
=a2−3
Hence at ∣a∣=3 , D=0 . So system don't have unique solution.
At a=4 , D=0 , So, system has unique solution. Hence not inconsistent.
At ∣a∣=3,D=0 and 2nd & 3rd equation are parallel. Hence no solution are possible.
Hence, system is inconsistent for ∣a∣=3