Easy MCQ +4 / -1 PYQ · JEE Mains 2021

If $$P = \left[ {\matrix{ 1 & 0 \cr {{1 \over 2}} & 1 \cr } } \right]$$, then P50 is :

  1. A $\left[ {\matrix{ 1 & 0 \cr {25} & 1 \cr } } \right]$ Correct answer
  2. B $\left[ {\matrix{ 1 & {50} \cr 0 & 1 \cr } } \right]$
  3. C $\left[ {\matrix{ 1 & {25} \cr 0 & 1 \cr } } \right]$
  4. D $\left[ {\matrix{ 1 & 0 \cr {50} & 1 \cr } } \right]$

Solution

$$P = \left[ {\matrix{ 1 &amp; 0 \cr {{1 \over 2}} &amp; 1 \cr } } \right]$$<br><br>$${P^2} = \left[ {\matrix{ 1 &amp; 0 \cr {{1 \over 2}} &amp; 1 \cr } } \right]\left[ {\matrix{ 1 &amp; 0 \cr {{1 \over 2}} &amp; 1 \cr } } \right] = \left[ {\matrix{ 1 &amp; 0 \cr 1 &amp; 1 \cr } } \right]$$<br><br>$${P^3} = \left[ {\matrix{ 1 &amp; 0 \cr 1 &amp; 1 \cr } } \right]\left[ {\matrix{ 1 &amp; 0 \cr {{1 \over 2}} &amp; 1 \cr } } \right] = \left[ {\matrix{ 1 &amp; 0 \cr {{3 \over 2}} &amp; 1 \cr } } \right]$$<br><br>$${P^4} = \left[ {\matrix{ 1 &amp; 0 \cr 1 &amp; 1 \cr } } \right]\left[ {\matrix{ 1 &amp; 0 \cr 1 &amp; 1 \cr } } \right] = \left[ {\matrix{ 1 &amp; 0 \cr 2 &amp; 1 \cr } } \right]$$<br><br>$\vdots$<br><br>$\therefore$ $${P^{50}} = \left[ {\matrix{ 1 &amp; 0 \cr {25} &amp; 1 \cr } } \right]$$

About this question

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

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