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MHT CET2018MathematicsMatrices

If A = 1 2 3 - 1 1 2 1 2 4 then A 2 - 5 A A - 1 =

Options

  1. A4 2 3 - 1 4 2 1 2 1
  2. B- 4 2 3 - 1 - 4 2 1 2 - 1
  3. C- 4 - 1 1 2 - 4 2 3 2 - 1
  4. D- 1 - 2 1 4 - 2 - 3 1 4 - 2

Correct answer

B. - 4 2 3 - 1 - 4 2 1 2 - 1

Step-by-step solution

( A 2 − 5 A ) A − 1 = A 2 ⋅ A − 1 − 5 A A − 1 = A − 5 I = [ 1 2 3 − 1 1 2 1 2 4 ] − [ 5 0 0 0 5 0 0 0 5 ] = [ − 4 2 3 − 1 − 4 2 1 2 − 1 ]

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