Q. 145.0( 2 Votes )

If show that (A2 – 5A + 7I) = O.

Answer :

Given :


Matrix A is of order 2 2.


To show : A2 - 5A +7I = 0


Formula used :



Where cij = ai1b1j + ai2b2j + ai3b3j + ……………… + ainbnj


If A is a matrix of order a b and B is a matrix of order c d ,then matrix AB exists and is of order a d ,if and only if b = c


A2 = = =


A2 =


5A = 5 × =


5A =


I =


7I = =


7I =


A2 - 5A + 7I = + = =


A2 - 5A + 7I = 0


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