NDA 2026
- Exam
- NDA
- Year
- 2026
- Subject
- Mathematics
- Chapter
- Matrices
NDA 2026 · Mathematics · Matrices
Consider the following statements : I. If n× n(n > 1) matrix is...
Consider the following statements :
I. If matrix is symmetric, then its inverse is also a symmetric matrix.
II. If matrix is singular, then its adjoint is also a singular matrix.
Which of the statements given above is/are correct ?
I. If matrix is symmetric, then its inverse is also a symmetric matrix.
II. If matrix is singular, then its adjoint is also a singular matrix.
Which of the statements given above is/are correct ?
Options
- AI only
- BII only
- CBoth I and II
- DNeither I nor II
Correct answer
C. Both I and II
Step-by-step solution
Let be an invertible symmetric matrix of order . Then .
We know that .
Substituting , we get .
Thus, the inverse of a symmetric matrix is also symmetric. The first statement is correct.
Let be a singular matrix of order . Then .
The determinant of the adjoint of is given by .
Since and , we have .
Thus, the adjoint of a singular matrix is also a singular matrix. The second statement is correct.
Both statements are correct.
Answer: Both I and II
We know that .
Substituting , we get .
Thus, the inverse of a symmetric matrix is also symmetric. The first statement is correct.
Let be a singular matrix of order . Then .
The determinant of the adjoint of is given by .
Since and , we have .
Thus, the adjoint of a singular matrix is also a singular matrix. The second statement is correct.
Both statements are correct.
Answer: Both I and II