The given system is:
x−5y+4z=λ
x+y−2z=0
2x−3y+z=0
Δ=∣∣
∣∣1−5411−22−31∣∣
∣∣
C1→C1+C2+C3
=∣∣
∣∣0−5401−20−31∣∣
∣∣=0
Hence, system is consistant only whenΔx=Δy=Δz=0.
Δx=∣∣
∣∣λ−5401−20−31∣∣
∣∣=−5λ=0
⇒λ=0
For λ=0 clearly Δy=Δz=0.
Therefore, system is consistent if λ=0.