Medium MCQ +4 / -1 PYQ · JEE Mains 2021

Let $$A = \left( {\matrix{ 1 & 0 & 0 \cr 0 & 1 & 1 \cr 1 & 0 & 0 \cr } } \right)$$. Then A2025 $-$ A2020 is equal to :

  1. A A<sup>6</sup> $-$ A Correct answer
  2. B A<sup>5</sup>
  3. C A<sup>5</sup> $-$ A
  4. D A<sup>6</sup>

Solution

$$A = \left[ {\matrix{ 1 &amp; 0 &amp; 0 \cr 0 &amp; 1 &amp; 1 \cr 1 &amp; 0 &amp; 0 \cr } } \right] \Rightarrow {A^2} = \left[ {\matrix{ 1 &amp; 0 &amp; 0 \cr 1 &amp; 1 &amp; 1 \cr 1 &amp; 0 &amp; 0 \cr } } \right]$$<br><br>$${A^3} = \left[ {\matrix{ 1 &amp; 0 &amp; 0 \cr 2 &amp; 1 &amp; 1 \cr 1 &amp; 0 &amp; 0 \cr } } \right] \Rightarrow {A^4} = \left[ {\matrix{ 1 &amp; 0 &amp; 0 \cr 3 &amp; 1 &amp; 1 \cr 1 &amp; 0 &amp; 0 \cr } } \right]$$<br><br>$${A^n} = \left[ {\matrix{ 1 &amp; 0 &amp; 0 \cr {n - 1} &amp; 1 &amp; 1 \cr 1 &amp; 0 &amp; 0 \cr } } \right]$$<br><br>$${A^{2025}} - {A^{2020}} = \left[ {\matrix{ 0 &amp; 0 &amp; 0 \cr 5 &amp; 0 &amp; 0 \cr 0 &amp; 0 &amp; 0 \cr } } \right]$$<br><br>$${A^6} - A = \left[ {\matrix{ 0 &amp; 0 &amp; 0 \cr 5 &amp; 0 &amp; 0 \cr 0 &amp; 0 &amp; 0 \cr } } \right]$$

About this question

Subject: Mathematics · Chapter: Matrices and Determinants · Topic: Types of Matrices and Operations

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