If A = [aᵢⱼ] is a 3×3 scalar matrix and a₁₁ = 7, then the matrix A is:

If A = [aᵢⱼ] is a 3×3 scalar matrix and a₁₁ = 7, then the matrix A is:

• A. Diagonal matrix with all diagonal entries 7
• B. Identity matrix
• C. Zero matrix
• D. Symmetric matrix only

Answer: A) Diagonal matrix with all diagonal entries 7

Explanation: A scalar matrix is a diagonal matrix where all diagonal elements are equal. Given a₁₁ = 7, all diagonal entries must be 7 and off-diagonal entries are 0. This is also symmetric and a multiple of identity, but the most specific description is a diagonal matrix with all diagonal entries 7.