The system of linear equations x+y+z=2 , 2x+y−z=3 , 3x+2y+kz=4 has a unique solution if
k≠0
−1<k<1
−2<k<2
k=0
The given system has a unique solution if
|11121−132k|≠0
Operate R1→R1+R2−R3
i.e., if −k(4−3)≠0
i.e., k≠0 .