Let S 1 and S 2 be respectively the sets of all a ∈ R - 0 for which the system of linear equations a x…

Let S1 and S2 be respectively the sets of all aR-0 for which the system of linear equations
ax+2ay-3az=1

2a+1 x+2a+3 y+a+1z=2

3a+5 x+a+5 y+a+2 z=3

has unique solution and infinitely many solutions. Then

  1. nS1=2 and S2 is an infinite set
  2. S1 is an infinite set an nS2=2
  3. S1=ϕ and S2=-0
  4. S1=-0 and S2=ϕ

Solution

Given,

S1 and S2 be respectively the sets of all aR-0 for which the system of linear equations


ax+2ay-3az=1 .........1

2a+1 x+2a+3 y+a+1z=2 ....2

3a+5 x+a+5 y+a+2 z=3 .....3

Now from above equations finding Δ=a2a-3a2a+12a+3a+13a+5a+5a+2

=a15a2+31a+36=0a=0

As 15a2+31a+36 cannot be zero as 312-4×15×36<0

So, Δ0 for all aR-0

Hence, S1=R-0 & S2=ϕ

Asked in: JEE Main 2023 (25 Jan Shift 1)

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