NCERT Exemplar Solutions
Class 12 - Mathematics - Chapter 4: DETERMINANTS
Fill in the Blanks

Question. 38

If A is a matrix of order 3 × 3, then |3A| = ____.

Answer:

27|A|

Question. 39

If A is an invertible matrix of order 3 × 3, then |A⁻¹| = ____.

Answer:

\( \dfrac{1}{|A|} \)

Question. 40

If x, y, z ∈ R, then the value of determinant

\( \begin{vmatrix} (2^x + 2^{-x})^2 & (2^x - 2^{-x})^2 & 1 \\ (3^x + 3^{-x})^2 & (3^x - 3^{-x})^2 & 1 \\ (4^x + 4^{-x})^2 & (4^x - 4^{-x})^2 & 1 \end{vmatrix} \)

is equal to ____.

Answer:

Zero

Question. 41

If cos 2θ = 0, then

\( \begin{vmatrix} 0 & \cos \theta & \sin \theta \\ \cos \theta & \sin \theta & 0 \\ \sin \theta & 0 & \cos \theta \end{vmatrix} \)

= ____.

Answer:

\( \dfrac{1}{2} \)

Question. 42

If A is a matrix of order 3 × 3, then (A²)⁻¹ = ____.

Answer:

(A⁻¹)²

Question. 43

If A is a matrix of order 3 × 3, then number of minors in determinant of A are ____.

Answer:

9

Question. 44

The sum of the products of elements of any row with the co-factors of corresponding elements is equal to ____.

Answer:

Value of the determinant

Question. 45

If x = −9 is a root of

\( \begin{vmatrix} x & 3 & 7 \\ 2 & x & 2 \\ 7 & 6 & x \end{vmatrix} = 0 \)

, then other two roots are ____.

Answer:

x = 2 y = 7

Question. 46

\( \begin{vmatrix} 0 & xyz & x - z \\ y - x & 0 & y - z \\ z - x & z - y & 0 \end{vmatrix} = \\ ____.

Answer:

(y - z)(z - x)(y - x + xyz)

Question. 47

If

\( f(x) = \begin{vmatrix} (1+x)^{17} & (1+x)^{19} & (1+x)^{23} \\ (1+x)^{23} & (1+x)^{29} & (1+x)^{34} \\ (1+x)^{41} & (1+x)^{43} & (1+x)^{47} \end{vmatrix} = A + Bx + Cx^2 + \ldots \)

then A = ____.

Answer:

Zero

NCERT Exemplar Solutions Class 12 – Mathematics – Chapter 4: DETERMINANTS – Fill in the Blanks | Detailed Answers