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If A=[1x01]A = \begin{bmatrix}1 & x \\0 & 1\end{bmatrix}A=[10​x1​]​ , then what is the value of AnA^nAn​ ? Where n is any natural nu
Question

If A=[1x01]A = \begin{bmatrix}1 & x \\0 & 1\end{bmatrix}​ , then what is the value of AnA^n​ ? Where n is any natural number.

A.

[nx0n]\begin{bmatrix}n & x \\0 & n\end{bmatrix}​​

B.

[nnx0n]\begin{bmatrix}n & nx \\0 & n\end{bmatrix}​​

C.

[1nx01]\begin{bmatrix}1 & nx \\0 & 1\end{bmatrix}​​

D.

[1xn01]\begin{bmatrix}1 & x^n \\0 & 1\end{bmatrix}​​

Correct option is C

Given:

A=[1x01]A = \begin{bmatrix}1 & x \\0 & 1\end{bmatrix}

​​Solution:

A1=[1x01]A^1 = \begin{bmatrix} 1 & x \\ 0 & 1 \end{bmatrix}

A2=AA=[1x01][1x01]=[11+x01x+x101+100x+11]=[12x01]A^2 = A \cdot A = \begin{bmatrix} 1 & x \\ 0 & 1 \end{bmatrix} \begin{bmatrix} 1 & x \\ 0 & 1 \end{bmatrix} = \begin{bmatrix} 1 \cdot 1 + x \cdot 0 & 1 \cdot x + x \cdot 1 \\ 0 \cdot 1 + 1 \cdot 0 & 0 \cdot x + 1 \cdot 1 \end{bmatrix} = \begin{bmatrix} 1 & 2x \\ 0 & 1 \end{bmatrix}

​​​A3=A2A=[12x01][1x01]=[11+2x01x+2x101+100x+11]=[13x01]A^3 = A^2 \cdot A = \begin{bmatrix} 1 & 2x \\ 0 & 1 \end{bmatrix} \begin{bmatrix} 1 & x \\ 0 & 1 \end{bmatrix} = \begin{bmatrix} 1 \cdot 1 + 2x \cdot 0 & 1 \cdot x + 2x \cdot 1 \\ 0 \cdot 1 + 1 \cdot 0 & 0 \cdot x + 1 \cdot 1 \end{bmatrix} = \begin{bmatrix} 1 & 3x \\ 0 & 1 \end{bmatrix}

By continuing this pattern, we observe that:

An=[1nx01]A^n = \begin{bmatrix} 1 & nx \\ 0 & 1 \end{bmatrix}

Thus, the correct answer is (c).

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