Discussion
\(\begin{vmatrix} 11 & 1 & 1 \\ 1 & 21 & 1 \\ 1 & 1 & 31 \end{vmatrix}\) is equal to
Answer: A
The determinant is 7100.
Expand along the first row:
\[ \begin{aligned} \Delta &= 11(21 \cdot 31 - 1) - 1(31 - 1) + 1(1 - 21) \\ &= 11(650) - 30 - 20 \\ &= 7150 - 50 = 7100 \end{aligned} \]
A quick check: the product of the diagonal, \(11 \times 21 \times 31 = 7161\), is close, and the off-diagonal ones reduce it slightly. 6800, 6900 and 6700 are too small, and 7300 is larger than the diagonal product.
No comment is present. Be the first to comment.
Loading…
Post your comment
Please log in or register to post a comment.
Examination Categories
- SSC Exams
- Banking Exams
- Teaching Exams
- Civil Services Exams
- Railways Exams
- Engineering Recruitment Exams
- Defence Exams
- State Government Exams
- Police Exams
- Insurance Exams
- Nursing Exams
- Other Government Exams
- NRA CET
- PG Entrance Exams
- Campus Placement
- MBA Entrance Exams
- CUET and UG Entrance
- Judiciary Exams
- Regulatory Body Exams
- Software Development