MCQ
If ${A^2} - A + I = 0$, then ${A^{ - 1}}$ =
  • A
    ${A^{ - 2}}$
  • B
    $A + I$
  • $I - A$
  • D
    $A - I$

Answer

Correct option: C.
$I - A$
c
(c) ${A^2} - A + I = 0$

==> $I = A - {A^2} \Rightarrow $$I = A(I - A)$

==> ${A^{ - 1}}I = {A^{ - 1}}(A(I - A))$ $ \Rightarrow $ ${A^{ - 1}} = I - A$.

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