Given, →A=3^i−2^j−^k
→B=2^i−3^j+2^k
→C=5^i−^j+2^k
→D=4^i−^j+λ^k
Since, the points A,B,C and D lie on the plane, therefore vectors −−→AB,−−→AC,−−→AD are coplanar.
⇒−−→AB⋅(−−→AC×−−→AD)=0
−−→AB=→B−→A=−^i−^j+3^k−−→AC=→C−→A=2^i+^j+3^k−−→AD=→D−→A=^i+^j+(λ+1)^k
⇒∣∣
∣∣−1−13213111+λ∣∣
∣∣=0
C1→C1−C2
⇒∣∣
∣∣0−13113011+λ∣∣
∣∣=0
⇒−λ−4=0⇒λ=−4