JEE Main 20257 AprilMorning Shift
- Exam
- JEE Main
- Year
- 2025
- Date
- 7 April
- Shift
- Morning Shift
- Subject
- Mathematics
- Chapter
- Matrices
JEE Main 2025 · 7 April · Morning Shift · Mathematics · Matrices
The number of singular matrices of order 2 , whose elements are...
The number of singular matrices of order 2 , whose elements are from the set is
Correct answer
36
Step-by-step solution
\left|\right|=$\mathrm{ad}-\mathrm{bc}$ \Rightarrow $\mathrm{ad}=\mathrm{bc}$<br/>Case-I Exactly 1 no. is used<br/>$\Rightarrow \text{ All singular }={ }^4 \mathrm{C}_1<br/>Case-II$ Exactly 2 no. is used<br/>$\Rightarrow{ }^4 \mathrm{C}_2 \times 2 \times 2$<br/>Case-III Exactly 3 no. is used<br/>None will be singular<br/>Case-IV Exactly 4 No. is used<br/>ad=bc<br/>\begin{aligned} & \Rightarrow 2 \times 9=3 \times 6 \\ & \left|\begin{array}{ll}9 & - \\ - & 2\end{array}\right| \Rightarrow{ }^4 \mathrm{C}_1\times 21\end{aligned}$=36$