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CUET · MATHS · PYQ PAPER 2023

If \(A\) is a square matrix such that \(A^2=A\), then the value of \((I-A)^2-(I+A)^3\) is :

  1. A \(-8 A\)
  2. B \(8 A\)
  3. C \(2(I-4 A)\)
  4. D \(2(I+4 A)\)
Verified Solution

Answer & Solution

Correct Answer

(A) \(-8 A\)

Step-by-step Solution

Detailed explanation

\((I-A)^2 = I^2 - 2IA + A^2 = I - 2A + A = I - A\) \((I+A)^3 = I^3 + 3I^2A + 3IA^2 + A^3 = I + 3A + 3A + A = I + 7A\) \((I-A)^2-(I+A)^3 = (I-A) - (I+7A)\) \(= I - A - I - 7A\) \(= -8A\)
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