JEE Main202325 Jan 2023Morning ShiftMathematicsDeterminantsActual
Let S 1 and S 2 be respectively the sets of all a ∈ R - 0 for which the system of linear equations a x + 2 a y - 3 a z = 1 2 a + 1 x + 2 a + 3 y + a + 1 z = 2 3 a + 5 x + a + 5 y + a + 2 z = 3 has unique solution and infinitely many solutions. Then
Options
- An S 1 = 2 and S 2 is an infinite set
- BS 1 is an infinite set an n S 2 = 2
- CS 1 = ϕ and S 2 = ℝ - 0
- DS 1 = ℝ - 0 and S 2 = ϕ
Correct answer
D. S 1 = ℝ - 0 and S 2 = ϕ
Step-by-step solution
Given, S 1 and S 2 be respectively the sets of all a ∈ R - 0 for which the system of linear equations a x + 2 a y - 3 a z = 1   . . . . . . . . . 1 2 a + 1   x + 2 a + 3   y + a + 1 z = 2   . . . . 2 3 a + 5   x + a + 5   y + a + 2   z = 3   . . . . . 3 Now from above equations finding Δ = a 2 a - 3 a 2 a + 1 2 a + 3 a + 1 3 a + 5 a + 5 a + 2 = a 15 a 2 + 31 a + 36 = 0 ⇒ a = 0 As 15 a 2 + 31 a + 36 cannot be zero as 31 2 - 4 × 15 × 36 < 0 So, &#