Skip to content
Part BCSIR NET December 2024check-membership-before-orthonormality

Check membership before orthonormality

Consider with the standard inner product. Let V be the subspace of spanned by the vectors (1, 0, 0, 1), (0, 1, 0, 1), and (0, 0, 1, 0). Which of the following is NOT an orthonormal basis of V?

  1. A.{}
  2. B.{}
  3. C.{}
  4. D.{}

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.

See pricing

50 are analysed free — try those first.

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 FormsGram–Schmidt, orthogonal/unitary/normal matrices, spectral theorem

ShareWhatsAppTelegram