हिंदी

If a = 1 3 ⎡ ⎢ ⎣ 1 1 2 2 1 − 2 X 2 Y ⎤ ⎥ ⎦ is Orthogonal, Then X + Y = - Mathematics

Advertisements
Advertisements

प्रश्न

If \[A = \frac{1}{3}\begin{bmatrix}1 & 1 & 2 \\ 2 & 1 & - 2 \\ x & 2 & y\end{bmatrix}\] is orthogonal, then x + y =

(a) 3
(b) 0
(c) − 3
(d) 1

विकल्प

  • 3

  • 0

  • -3

  • 1

  • None of these

MCQ

उत्तर

None of these

\[\text{ We have, }A = \frac{1}{3}\begin{bmatrix}1 & 1 & 2 \\ 2 & 1 & - 2 \\ x & 2 & y\end{bmatrix}\]
\[ \Rightarrow A^T = \frac{1}{3}\begin{bmatrix}1 & 2 & x \\ 1 & 1 & 2 \\ 2 & - 2 & y\end{bmatrix}\]
\[\text{ Now,} A^T A = I\]
\[ \Rightarrow \begin{bmatrix}x^2 + 5 & 2x + 3 & xy - 2 \\ 3 + 2x & 6 & 2y \\ xy - 6 & 2y & y^2 + 8\end{bmatrix} = \begin{bmatrix}9 & 0 & 0 \\ 0 & 9 & 0 \\ 0 & 0 & 9\end{bmatrix}\]
The corresponding elements of two equal matrices are not equal . 
Thus, the matrix A is not orthogonal .

shaalaa.com
  क्या इस प्रश्न या उत्तर में कोई त्रुटि है?
अध्याय 7: Adjoint and Inverse of a Matrix - Exercise 7.4 [पृष्ठ ३८]

APPEARS IN

आरडी शर्मा Mathematics [English] Class 12
अध्याय 7 Adjoint and Inverse of a Matrix
Exercise 7.4 | Q 25 | पृष्ठ ३८

संबंधित प्रश्न

Verify A (adj A) = (adj A) A = |A|I.

`[(2,3),(-4,-6)]`


Find the inverse of the matrices (if it exists).

`[(-1,5),(-3,2)]`


Let `A =[(3,7),(2,5)] and B = [(6,8),(7,9)]`. Verify that `(AB)^(-1) = B^(-1)A^(-1).`


If x, y, z are nonzero real numbers, then the inverse of matrix A = `[(x,0,0),(0,y,0),(0,0,z)]` is ______.


Let A = `[(1, sin theta, 1),(-sin theta,1,sin 1),(-1, -sin theta, 1)]` where 0 ≤ θ≤ 2π, then ______.


Find the adjoint of the following matrix:
\[\begin{bmatrix}\cos \alpha & \sin \alpha \\ \sin \alpha & \cos \alpha\end{bmatrix}\]

Verify that (adj A) A = |A| I = A (adj A) for the above matrix.

Compute the adjoint of the following matrix:

\[\begin{bmatrix}2 & - 1 & 3 \\ 4 & 2 & 5 \\ 0 & 4 & - 1\end{bmatrix}\]

Verify that (adj A) A = |A| I = A (adj A) for the above matrix.


If  \[A = \begin{bmatrix}- 4 & - 3 & - 3 \\ 1 & 0 & 1 \\ 4 & 4 & 3\end{bmatrix}\], show that adj A = A.


Find the inverse of the following matrix:

\[\begin{bmatrix}0 & 1 \\ 1 & 0\end{bmatrix}\]

Find the inverse of the following matrix.

\[\begin{bmatrix}0 & 1 & - 1 \\ 4 & - 3 & 4 \\ 3 & - 3 & 4\end{bmatrix}\]

Given \[A = \begin{bmatrix}2 & - 3 \\ - 4 & 7\end{bmatrix}\], compute A−1 and show that \[2 A^{- 1} = 9I - A .\]


Let
\[F \left( \alpha \right) = \begin{bmatrix}\cos \alpha & - \sin \alpha & 0 \\ \sin \alpha & \cos \alpha & 0 \\ 0 & 0 & 1\end{bmatrix}\text{ and }G\left( \beta \right) = \begin{bmatrix}\cos \beta & 0 & \sin \beta \\ 0 & 1 & 0 \\ - \sin \beta & 0 & \cos \beta\end{bmatrix}\]

Show that

(i) \[\left[ F \left( \alpha \right) \right]^{- 1} = F \left( - \alpha \right)\]
(ii) \[\left[ G \left( \beta \right) \right]^{- 1} = G \left( - \beta \right)\]
(iii) \[\left[ F \left( \alpha \right)G \left( \beta \right) \right]^{- 1} = G \left( - \beta \right)F \left( - \alpha \right)\]

Show that

\[A = \begin{bmatrix}- 8 & 5 \\ 2 & 4\end{bmatrix}\] satisfies the equation \[A^2 + 4A - 42I = O\]. Hence, find A−1.

If \[A = \begin{bmatrix}3 & 1 \\ - 1 & 2\end{bmatrix}\], show that 

\[A^2 - 5A + 7I = O\].  Hence, find A−1.

Show that \[A = \begin{bmatrix}5 & 3 \\ - 1 & - 2\end{bmatrix}\] satisfies the equation \[x^2 - 3x - 7 = 0\]. Thus, find A−1.


If \[A = \begin{bmatrix}- 1 & 2 & 0 \\ - 1 & 1 & 1 \\ 0 & 1 & 0\end{bmatrix}\] , show that  \[A^2 = A^{- 1} .\]


Solve the matrix equation \[\begin{bmatrix}5 & 4 \\ 1 & 1\end{bmatrix}X = \begin{bmatrix}1 & - 2 \\ 1 & 3\end{bmatrix}\], where X is a 2 × 2 matrix.


\[\text{ If }A^{- 1} = \begin{bmatrix}3 & - 1 & 1 \\ - 15 & 6 & - 5 \\ 5 & - 2 & 2\end{bmatrix}\text{ and }B = \begin{bmatrix}1 & 2 & - 2 \\ - 1 & 3 & 0 \\ 0 & - 2 & 1\end{bmatrix},\text{ find }\left( AB \right)^{- 1} .\]

Find the inverse by using elementary row transformations:

\[\begin{bmatrix}1 & 6 \\ - 3 & 5\end{bmatrix}\]


Find the inverse by using elementary row transformations:

\[\begin{bmatrix}2 & 5 \\ 1 & 3\end{bmatrix}\]


Find the inverse by using elementary row transformations:

\[\begin{bmatrix}1 & 2 & 0 \\ 2 & 3 & - 1 \\ 1 & - 1 & 3\end{bmatrix}\]


Find the inverse by using elementary row transformations:

\[\begin{bmatrix}1 & 3 & - 2 \\ - 3 & 0 & - 1 \\ 2 & 1 & 0\end{bmatrix}\]


If A is a square matrix, then write the matrix adj (AT) − (adj A)T.


If A is a non-singular symmetric matrix, write whether A−1 is symmetric or skew-symmetric.


If \[A = \begin{bmatrix}\cos \theta & \sin \theta \\ - \sin \theta & \cos \theta\end{bmatrix}\text{ and }A \left( adj A = \right)\begin{bmatrix}k & 0 \\ 0 & k\end{bmatrix}\], then find the value of k.


Find the inverse of the matrix \[\begin{bmatrix}3 & - 2 \\ - 7 & 5\end{bmatrix} .\]


If \[A = \begin{bmatrix}1 & - 3 \\ 2 & 0\end{bmatrix}\], write adj A.


If A is an invertible matrix of order 3, then which of the following is not true ?


If A, B are two n × n non-singular matrices, then __________ .


If A satisfies the equation \[x^3 - 5 x^2 + 4x + \lambda = 0\] then A-1 exists if _____________ .


If d is the determinant of a square matrix A of order n, then the determinant of its adjoint is _____________ .


If \[A = \begin{bmatrix}1 & 0 & 1 \\ 0 & 0 & 1 \\ a & b & 2\end{bmatrix},\text{ then aI + bA + 2 }A^2\] equals ____________ .


If A = `[(0, 1, 3),(1, 2, x),(2, 3, 1)]`, A–1 = `[(1/2, -4, 5/2),(-1/2, 3, -3/2),(1/2, y, 1/2)]` then x = 1, y = –1.


|A–1| ≠ |A|–1, where A is non-singular matrix.


Find the adjoint of the matrix A `= [(1,2),(3,4)].`


Find the adjoint of the matrix A, where A `= [(1,2,3),(0,5,0),(2,4,3)]`


Find x, if `[(1,2,"x"),(1,1,1),(2,1,-1)]` is singular


Find the value of x for which the matrix A `= [(3 - "x", 2, 2),(2,4 - "x", 1),(-2,- 4,-1 - "x")]` is singular.


Given that A is a square matrix of order 3 and |A| = –2, then |adj(2A)| is equal to ______.


Share
Notifications

Englishहिंदीमराठी


      Forgot password?
Use app×