Final answer:
The matrix A₄ is a 4x4 matrix with entries given by x and y in specific positions.
Step-by-step explanation:
The matrix A₄ is a 4x4 matrix with entries given by:
A₁₁ = x, A₁₂ = 0, A₁₃ = 0, A₁₄ = y
A₂₁ = 0, A₂₂ = x, A₂₃ = y, A₂₄ = 0
A₃₁ = 0, A₃₂ = y, A₃₃ = x, A₃₄ = 0
A₄₁ = y, A₄₂ = 0, A₄₃ = 0, A₄₄ = x