Q18 of 74 Page 7

Show that satisfies the equation A2 + 4A – 42I = O. Hence, find A – 1.

A =


A2 = =


=


4A = 4


42I = 42


Now,


A2 + 4A – 42I =


=


Hence, =


Now, A2 + 4A – 42I = 0


= A – 1. A . A + 4 A – 1.A – 42 A – 1.I = 0


= IA + 4I – 42A – 1 = 0


= 42A – 1 = A + 4I


= A – 1 =


=


A – 1 =


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