Question: (Eigenvectors of a symmetric 2 × 2 matrix) Let p, q ∈ Rn be two linearly independent vectors, with unit norm (||p||2 = ||q||2 = 1). Define the symmetric matrix A ? pq? + qp?. In your derivations, it may be useful to use the notation c ? p?q.
1. Show that p + q and p - q are eigenvectors of A, and determine the corresponding eigenvalues.
2. Determine the null space and rank of A.
3. Find an eigenvalue decomposition of A, in terms of p, q.