NCERT Exemplar Solutions
Class 12 - Mathematics - Chapter 3: Matrices
Fill in the Blanks

Question. 68

_____ matrix is both symmetric and skew symmetric matrix.

Answer:

Null matrix

Question. 69

Sum of two skew symmetric matrices is always _____ matrix.

Answer:

Skew symmetric matrix

Question. 70

The negative of a matrix is obtained by multiplying it by _____.

Answer:

-1

Question. 71

The product of any matrix by the scalar _____ is the null matrix.

Answer:

0

Question. 72

A matrix which is not a square matrix is called a _____ matrix.

Answer:

Rectangular matrix

Question. 73

Matrix multiplication is _____ over addition.

Answer:

Distributive

Question. 74

If A is a symmetric matrix, then A\(^3\) is a _____ matrix.

Answer:

Symmetric matrix

Question. 75

If A is a skew symmetric matrix, then A\(^2\) is a ____.

Answer:

Symmetric matrix

Question. 77

If A is skew symmetric, then kA is a _____ (k is any scalar).

Answer:

Skew symmetric matrix

Question. 79

If A is symmetric matrix, then B'AB is ____.

Answer:

Symmetric matrix

Question. 80

If A and B are symmetric matrices of same order, then AB is symmetric if and only if ____.

Answer:

AB = BA

Question. 81

In applying one or more row operations while finding A\(^{-1}\) by elementary row operations, we obtain all zeros in one or more, then A\(^{-1}\) ____.

Answer:

does not exist

Question. 76_i

If A and B are square matrices of the same order, then (i) (AB)' = ____.

Answer:

B' A'

Question. 76_ii

(ii) (kA)' = ____ (k is any scalar)

Answer:

kA

Question. 76_iii

(iii) [k(A − B)]' = ____.

Answer:

k(A − B)

Question. 78_i

If A and B are symmetric matrices, then (i) AB − BA is a ____.

Answer:

Skew symmetric matrix

Question. 78_ii

(ii) BA − 2AB is a ____.

Answer:

neither symmetric nor skew symmetric matrix

NCERT Exemplar Solutions Class 12 – Mathematics – Chapter 3: Matrices – Fill in the Blanks | Detailed Answers