® A = [aij]n × n is  an identity matrix, if aij = 1, when i = j, aij = 0, when i ≠ j ® A zero matrix has all its elements as zero ® A = [aij] = [bij] = B if (i) A and B are of same order, (ii)  aij = bij for all
possible values of i and j α
β
γ
−α




Rationalised 2023-24
 74
MATHEMATICS
® kA = k[aij]m × n = [k(aij)]m × n
® – A = (–1)A
® A – B = A + (–1) B
® A + B = B + A
® (A + B) + C = A + (B + C), where A, B and C are of same order