- Exam
- JEE Main
- Year
- 2024
- Date
- 31 January
- Shift
- Evening Shift
- Subject
- Mathematics
- Chapter
- Determinants
JEE Main 2024 · 31 January · Evening Shift · Mathematics · Determinants
Let A be a 3 × 3 real matrix such that A( array ll 1 0 1 array ) =...
Let A be a real matrix such that A\left(\right) = 2\left(\right), A\left(\right) = 4\left(\right), A\left(\right) = 2\left(\right). Then, the system \left(A - 3I\right)\left(\right) = \left(\right)$ has
Options
- Aunique solution
- Bexactly two solutions
- Cno solution
- Dinfinitely many solutions
Correct answer
A. unique solution
Step-by-step solution
Let, A = \left[\begin{cases}{x}_{1} & {y}_{1} & {z}_{1} \\ {x}_{2} & {y}_{2} & {z}_{2} \\ {x}_{3} & {y}_{3} & {z}_{3}\end{cases}\right]
It is given that, A\left[\right] = \left[\right]
⇒ \left[\right] = \left[\right]
Also, A\left[\right] = \left[\right]
⇒ \left[\right] = \left[\right]
Now, A\left[\right] = \left[\right]
⇒ \left[\right] = \left[\right]
Using \left(i\right)\text{and}\left(ii\right)⇒ {x}_{1} = 3, {x}_{2} = 0, {x}_{3} = - 1⇒ {z}_{1} = - 1, {z}_{2} = 0, {z}_{3} = 3∴ A = \left[\right]</p><p>Now, \left(A - 3I\right)\left[\right] = \left[\right]
⇒ \left[\begin{cases}0 & 0 & - 1 \\ 0 & - 1 & 0 \\ - 1 & 0 & 0\end{cases}\right]\left[\right] = \left[\right]
⇒ \left[\right] = \left[\right]