JAMIA 2021 — Mathematics PYQ
JAMIA | Mathematics | 2021If A and B are matrices of same order, then (AB’ – BA’) is a
Choose the correct answer:
- A. Skew-symmetric matrix(Correct Answer)
- B. Null matrix
- C. Symmetric matrix
- D. Unit matrix
Skew-symmetric matrix
Explanation
Properties of Matrices
Given that A and B are matrices of the same order. Let C=AB′−BA′.
To determine the nature of matrix C, we find its transpose C′:
C′=(AB′−BA′)′
Using the property (X−Y)′=X′−Y′:
C′=(AB′)′−(BA′)′
Using the property (XY)′=Y′X′ and (X′)′=X:
C′=(B′)′A′−(A′)′B′
C′=BA′−AB′
Comparison
Now, factor out a negative sign:
C′=−(AB′−BA′)
C′=−C
Conclusion
A square matrix C is called skew-symmetric if C′=−C.
Final Answer:
The matrix (AB′−BA′) is a Skew-Symmetric Matrix.
Explanation
Properties of Matrices
Given that A and B are matrices of the same order. Let C=AB′−BA′.
To determine the nature of matrix C, we find its transpose C′:
C′=(AB′−BA′)′
Using the property (X−Y)′=X′−Y′:
C′=(AB′)′−(BA′)′
Using the property (XY)′=Y′X′ and (X′)′=X:
C′=(B′)′A′−(A′)′B′
C′=BA′−AB′
Comparison
Now, factor out a negative sign:
C′=−(AB′−BA′)
C′=−C
Conclusion
A square matrix C is called skew-symmetric if C′=−C.
Final Answer:
The matrix (AB′−BA′) is a Skew-Symmetric Matrix.

