Q22 of 74 Page 7

Show that satisfies the equation x2 – 3A – 7 = 0. Thus, find A – 1.

A =


A2 =


=


Now, A2 – 3A – 7 = 0


=


=


=


So, A2 – 3A – 7I = 0


Multiply by A – 1 both sides


= A.A. A – 1 – 3A. A – 1 – 7I. A – 1 = 0


= A – 3I – 7A – 1 = 0


= 7A – 1 = A – 3I


= A – 1 =


Hence, A – 1 =


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