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Question: Answered & Verified by Expert
The set of all values of λ for which the system of linear equations:
2 x 1 - 2 x 2 + x 3 = λ x 1
2 x 1 - 3 x 2 + 2 x 3 = λ x 2
- x 1 + 2 x 2 = λ x 3
has a non-trivial solution,
MathematicsDeterminantsJEE MainJEE Main 2015 (04 Apr)
Options:
  • A Contains more than two elements.
  • B Is an empty set.
  • C Is a singleton.
  • D Contains two elements.
Solution:
1972 Upvotes Verified Answer
The correct answer is: Contains two elements.
2 - λ x 1 - 2 x 2 + x 3 = 0

2 x 1 - λ + 3 x 2 + 2 x 3 = 0

- x 1 + 2 x 2 - λ x 3 = 0

The systems of linear equations will have a non-trivial solution

⇒     2 - λ - 2 1 2 - λ - 3 2 - 1 2 - λ = 0

⇒     2 - λ λ 2 + 3 λ - 4 + 2 - 2 λ + 2 + 1 4 - λ - 3 = 0

2 λ 2 + 6 λ - 8 - λ 3 - 3 λ 2 + 4 λ - 4 λ + 4 + 1 - λ = 0

- λ 3 - λ 2 + 5 λ - 3 = 0

λ 3 + λ 2 - 5 λ + 3 = 0

λ - 1 λ 2 + 2 λ - 3 = 0

λ - 1 λ + 3 λ - 1 = 0

⇒    λ = -3 , 1 , 1

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