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Part CCSIR NET December 2024matching-coefficients-gives-c3-equals-c2-either-way

Matching coefficients gives c3 equals c2 either way

Let (V, ⟨ , ⟩) be an inner product space over C\mathbb{C} and T : V → V be aC−a \mathbb{C}-linear transformation. Let v1v_{1} and v2v_{2} be non-zero vectors in V such that Tv1=c1v1_{1} = c_{1}v_{1} and Tv2=c2v2_{2} = c_{2}v_{2} for some c1,c2∈Cc_{1}, c_{2} \in \mathbb{C}. Let v3=v2−(v_{3} = v_{2} - (⟨v2,v1v_{2}, v_{1}⟩/‖v1v_{1}‖2)v1^{2})v_{1}. Suppose that v3v_{3} is non-zero and Tv3=c3v3_{3} = c_{3}v_{3} for some c3∈Cc_{3} \in \mathbb{C}. Which of the following statements are true?

  1. A.The set {v1,v2v_{1}, v_{2}} is linearly independent.✓ Correct
  2. B.If c1≠c2c_{1} \ne c_{2}, then ⟨v1,v2v_{1}, v_{2}⟩ = 0.✓ Correct
  3. C.If c1=c2c_{1} = c_{2}, then c3=c2c_{3} = c_{2}.✓ Correct
  4. D.If c1≠c2c_{1} \ne c_{2}, then c3=c2c_{3} = c_{2}.✓ Correct

You have the answer. Trap Analysis is why the other three were written.

Not a worked solution repeated four times — the specific reasoning error each wrong option was built to reward, and why this one tests execution slip.

See pricing

50 are analysed free — try those first.

The trap it tests

Execution slip

The idea was right. The computation was not.

Drill statements like this

Related counterexample: A real matrix with all real eigenvalues is orthogonally diagonalisable

More on this topic

The chapter behind this: Inner products, orthogonality and the spectral theorem — free to read

From Inner Product Spaces and Forms › Gram–Schmidt, orthogonal/unitary/normal matrices, spectral theorem

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