MCQ
If $A$ is a square matrix and $A^2=A,$ then $(I+A)^2-3 A$ is equal to
  • $I$
  • B
    $A$
  • C
    $2A$
  • D
    $3I$

Answer

Correct option: A.
$I$
Given that $A^2=A$
Consider $(I+A)^2-3 A=I^2+A^2+2 A I-3 A$
$=I+A+2 A-3 A  \ \left[\because I^2=I, A^2=A \text { (given) }\right]$
$=I$

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