Q34 / 90 · JEE Main 2021 (17 Mar Shift 1) · Mathematics

The system of equations kx+y+z=1, x+ky+z=k and x+y+zk=k2 has no solution if k is equal to:

  • A
    0
  • B
    1
  • C
    -1
  • Correct answer
    D
    -2

Solution

kx+y+z=1

x+ky+z=k

x+y+zk=k2

Δ=K111K111K=KK2-1-1K-1+11-K

=K3-K-K+1+1-K

=K3-3 K+2

=(K-1)2 K+2

For K=1

Δ=Δ1=Δ2=Δ3=0

But for K=-2, at least one out of Δ1,Δ2,Δ3 are not zero

Hence for no solution, K=-2

Hence, the correct answer is option: 'D'.

Relevant Questions