- Exam
- JEE Main
- Year
- 2021
- Date
- 25 July
- Shift
- Evening Shift
- Subject
- Mathematics
- Chapter
- Matrices
JEE Main 2021 · 25 July · Evening Shift · Mathematics · Matrices
If P = [ cases 1 & 0 (1)/(2) & 1 cases ], then P ^ 50 is:
Options
- A\left[\begin{cases}1 & 0 \\ 25 & 1\end{cases}\right]
- B\left[\begin{cases}1 & 50 \\ 0 & 1\end{cases}\right]
- C\left[\begin{cases}1 & 25 \\ 0 & 1\end{cases}\right]
- D\left[\begin{cases}1 & 0 \\ 50 & 1\end{cases}\right]
Correct answer
A. \left[\begin{cases}1 & 0 \\ 25 & 1\end{cases}\right]
Step-by-step solution
P = \left[\begin{cases}1 & 0 \\ \dfrac{1}{2} & 1\end{cases}\right]
{P}^{2} = \left[\begin{cases}1 & 0 \\ \dfrac{1}{2} & 1\end{cases}\right]\left[\begin{cases}1 & 0 \\ \dfrac{1}{2} & 1\end{cases}\right] = \left[\begin{cases}1 & 0 \\ 1 & 1\end{cases}\right]
{P}^{3} = \left[\begin{cases}1 & 0 \\ 1 & 1\end{cases}\right]\left[\begin{cases}1 & 0 \\ \dfrac{1}{2} & 1\end{cases}\right] = \left[\begin{cases}1 & 0 \\ \dfrac{3}{2} & 1\end{cases}\right]
{P}^{4} = \left[\begin{cases}1 & 0 \\ \dfrac{1}{2} & 1\end{cases}\right]\left[\begin{cases}1 & 0 \\ \dfrac{3}{2} & 1\end{cases}\right] = \left[\begin{cases}1 & 0 \\ 2 & 1\end{cases}\right]
∴ {P}^{50} = \left[\begin{cases}1 & 0 \\ \dfrac{1}{2} + 49\left(\dfrac{1}{2}\right) & 1\end{cases}\right] = \left[\begin{cases}1 & 0 \\ 25 & 1\end{cases}\right]