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CBSE Class 12 Math 2023 Delhi Set 1 Solved Paper

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Question : 4 of 38
Marks: +1, -0
If A=[1021],B=[x011]A=\begin{bmatrix}1&0\\2&1\end{bmatrix}, B=\begin{bmatrix}x&0\\1&1\end{bmatrix} and A=B2A=B^2, then xx equals:
Solution:     👈: Video Solution
A  =B2A \; = B^2
  [1021]  =[x011][x011]\; \begin{bmatrix}1&0\\2&1\end{bmatrix} \; = \begin{bmatrix}x&0\\1&1\end{bmatrix}\begin{bmatrix}x&0\\1&1\end{bmatrix}
∴      [1021]  =[x20x+11]\therefore \; \; \; \begin{bmatrix}1&0\\2&1\end{bmatrix} \; = \begin{bmatrix}x^2&0\\x+1&1\end{bmatrix}
∴  x2  =1   and   x+1=2\therefore \; x^2 \; = 1 \; \text{ and } \; x+1=2
∴      x  =±1\therefore \; \; \; x \; = \pm 1
  x  =1\; x \; = 1
Hence x=1x=1
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