If find k such that A2 – 8A + kI – 0.

Given:


I is identity matrix, so


Also given,


Now, we will find the matrix for A2, we get




[as cij = ai1b1j + ai2b2j + … + ainbnj]



Now, we will find the matrix for 8A, we get





So,



Substitute corresponding values from eqn(i) and (ii), we get




[as rij = aij + bij + cij],


And to satisfy the above condition of equality, the corresponding entries of the matrices should be equal


Hence,


Therefore, the value of k is 7


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