For system to be inconsistent D=∣−1321−a−225−a∣=0
⇒a2−7a+12=0⇒a=3,4
Dx=∣0171−a−225−a∣=15a+31
Dx=0 for a=3,4
Similarly we can show Dy=0,Dz=0 for a=3,4
⇒n(S1)=2
Now for infinitely many solutions D=0also Dx=Dy=Dz=0 which is not possible value of any real of a, since D=0&{D}_{x}=0 have different solutions for a
⇒n(S2)=0
Hence, n({S}_{1})=2&n({S}_{2})=0