Before You Begin
Question #41273
The Question
Let be an integer. Consider the determinant Let be the term independent of in the binomial expansion of . For an integer , a matrix is defined as: Find the number of valid values of such that no row of is a zero vector.
Options
- A.
24
- B.
2
- C.
60
- D.
82
Check Your Answer
Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Specialist
Targeted practice for niche, high-difficulty concepts that frequently appear in JEE Advanced exams.
Concepts Behind This Question
Elementary Row Operation Invariance|Term Independent of x|Complementary Counting|Mutually Exclusive vs Independent
Why This Question Is Tricky
Common Mistakes
This question tests the student's ability to combine determinant simplification using elementary row operations with set theory and probability concepts.
The first phase requires recognizing Pascal's identity to reduce the determinant to a simple binomial, leading to the term independent of y ().
The core trap lies in the second phase: counting the valid integers .
Students must find the complement of the union of three events (rows being zero vectors).
A common fatal mistake is assuming these events are 'Mutually Exclusive' rather than 'Independent'.
If they simply add the individual counts () and subtract from 84, they arrive at the trap answer 2.
Recognizing that divisibility by coprime numbers forms independent events allows the correct use of the inclusion-exclusion principle or direct multiplication of independent probabilities to find the true count of 24.
Quick Facts About This Question
Question Information
| Subject | Mathematics |
| Chapter | Determinants - Class 12 |
| Concept | Elementary Row Operation Invariance |
| Difficulty | 8 |
| Cognitive Load | 7 |
| Target Solve Time | 160 sec |
| Access | Free |