Target Exam

CUET

Subject

-- Mathematics - Section B1

Chapter

Matrices

Question:

If $A=\begin{bmatrix} 1& 0 \\\frac{1}{3} & 1\end{bmatrix}$ then $A^{48}$ is :

Options:

$\begin{bmatrix} 1& 0 \\1 & 15\end{bmatrix}$

$\begin{bmatrix} 1& 0 \\16 & 1\end{bmatrix}$

$\begin{bmatrix} 0& 1 \\16 & 1\end{bmatrix}$

$\begin{bmatrix} 1& 0 \\15 & 1\end{bmatrix}$

Correct Answer:

$\begin{bmatrix} 1& 0 \\16 & 1\end{bmatrix}$

Explanation:

The correct answer is Option (2) → $\begin{bmatrix} 1& 0 \\16 & 1\end{bmatrix}$

$A=\begin{bmatrix} 1& 0 \\\frac{1}{3} & 1\end{bmatrix}$

$A^2=\begin{bmatrix} 1& 0 \\\frac{2}{3} & 1\end{bmatrix}$

$A^3=\begin{bmatrix} 1& 0 \\\frac{3}{3} & 1\end{bmatrix}$

$⇒A^n=\begin{bmatrix} 1& 0 \\\frac{n}{3} & 1\end{bmatrix}⇒A^{48}=\begin{bmatrix} 1& 0 \\\frac{48}{3} & 1\end{bmatrix}$

$=\begin{bmatrix} 1& 0 \\16 & 1\end{bmatrix}$