Let \(A = [a_{ij}]\) be a square matrix of order 3 whose elements are given by \(a_{ij} = i^2 - j\). The sum of the diagonal elements of A is
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → 8
The diagonal elements are the elements with i = j, that is \(a_{11}\), \(a_{22}\) and \(a_{33}\).
\(a_{11} = 1^2 - 1 = 0\)
\(a_{22} = 2^2 - 2 = 2\)
\(a_{33} = 3^2 - 3 = 6\)
Hence the sum of the diagonal elements is
\(0 + 2 + 6 = 8\)