If \[A = \left[ {\begin{array}{*{20}{c}}0&0&1\\0&1&0\\1&0&0\end{array}} \right]\], then find the value of \[{A^{ - 1}}\].
A. \[I\]
B. \[ - I\]
C. \[ - A\]
D. \[A\]
Answer
298.8k+ views
Hint: First, calculate the determinant of the given matrix. Then calculate the adjoint matrix of the given matrix. In the end, substitute the values in the formula for the inverse of the matrix and get the required answer.
Formula used:
The determinant of a \[3 \times 3\] matrix \[A = \left[ {\begin{array}{*{20}{c}}{{a_{11}}}&{{a_{12}}}&{{a_{13}}}\\{{a_{21}}}&{{a_{22}}}&{{a_{23}}}\\{{a_{31}}}&{{a_{32}}}&{{a_{33}}}\end{array}} \right]\] is: \[\left| A \right| = {a_{11}}\left( {{a_{22}}{a_{33}} - {a_{32}}{a_{23}}} \right) - {a_{12}}\left( {{a_{21}}{a_{33}} - {a_{31}}{a_{23}}} \right) + {a_{13}}\left( {{a_{21}}{a_{32}} - {a_{31}}{a_{22}}} \right)\]
The inverse matrix of a non-singular matrix \[A\] is: \[{A^{ - 1}} = \dfrac{1}{{\left| A \right|}}\left( {adj A} \right)\]
Complete step by step solution:
The given matrix is \[A = \left[ {\begin{array}{*{20}{c}}0&0&1\\0&1&0\\1&0&0\end{array}} \right]\].
Let’s calculate the determinant of the given matrix.
Apply the formula of the determinant of a \[3 \times 3\] matrix.
We get,
\[\left| A \right| = 0\left( {0 - 0} \right) - 0\left( {0 - 0} \right) + 1\left( {0 - 1} \right)\]
\[ \Rightarrow \left| A \right| = - 1\] \[.....\left( 1 \right)\]
Now calculate the adjoint matrix of the given matrix by using the co-factor method.
Let’s calculate the co-factors of the matrix.
\[{A_{11}} ={\left( { - 1} \right)^{1 + 1}}\left[ {\begin{array}{*{20}{c}}1&0\\0&0\end{array}} \right]
= {\left( { - 1} \right)^{1 + 1}}\left( {1 \times 0 - 0 \times 0} \right) = 0\]
\[{A_{12}} =\left[ {\begin{array}{*{20}{c}}0&0\\1&0\end{array}} \right]
= {\left( { - 1} \right)^{1 + 3}}{\left( { - 1} \right)^{1 + 2}}\left( {0 \times 0 - 1 \times 0} \right) = 0\]
\[{A_{13}} ={\left( { - 1} \right)^{1 + 3}}\left[ {\begin{array}{*{20}{c}}0&1\\1&0\end{array}} \right]
= {\left( { - 1} \right)^{1 + 3}}\left( {0 \times 0 - 1 \times 1} \right) = - 1\]
\[{A_{21}} ={\left( { - 1} \right)^{2 + 1}}\left[ {\begin{array}{*{20}{c}}0&1\\0&0\end{array}} \right]
= {\left( { - 1} \right)^{2 + 1}}\left( {0 \times 0 - 0 \times 1} \right) = 0\]
\[{A_{22}} ={\left( { - 1} \right)^{2 + 2}} \left[ {\begin{array}{*{20}{c}}0&1\\1&0\end{array}} \right]
={\left( { - 1} \right)^{2 + 2}}\left( {0 \times 0 - 1 \times 1} \right) = - 1\]
\[{A_{23}} ={\left( { - 1} \right)^{2 + 3}}\left[ {\begin{array}{*{20}{c}}0&0\\1&0\end{array}} \right]
= {\left( { - 1} \right)^{2 + 3}}\left( {0 \times 0 - 1 \times 0} \right) = 0\]
\[{A_{31}} ={\left( { - 1} \right)^{3 + 1}}\left[ {\begin{array}{*{20}{c}}0&1\\1&0\end{array}} \right]
= {\left( { - 1} \right)^{3 + 1}}\left( {0 \times 0 - 1 \times 1} \right) = - 1\]
\[{A_{32}} ={\left( { - 1} \right)^{3 + 2}} \left[ {\begin{array}{*{20}{c}}0&1\\0&0\end{array}} \right] ={\left( { - 1} \right)^{3 + 2}}\left( {0 \times 0 - 1 \times 0} \right) = 0\]
\[{A_{33}} = {\left( { - 1} \right)^{3 + 3}}\left[ {\begin{array}{*{20}{c}}0&0\\0&1\end{array}} \right]= {\left( { - 1} \right)^{3 + 3}}\left( {0 \times 1 - 0 \times 0} \right) = 0\]
So, the co-factor matrix of the given matrix is \[\left[ {\begin{array}{*{20}{c}}0&0&{ - 1}\\0&{ - 1}&0\\{ - 1}&0&0\end{array}} \right]\].
We know that the cofactor matrix is the transpose of the adjoint matrix.
So, the adjoint matrix of the given matrix is,
\[adj A = \left[ {\begin{array}{*{20}{c}}0&0&{ - 1}\\0&{ - 1}&0\\{ - 1}&0&0\end{array}} \right]\] \[.....\left( 2 \right)\]
Substitute the equations \[\left( 1 \right)\] and \[\left( 2 \right)\] in the formula of the inverse matrix \[{A^{ - 1}} = \dfrac{1}{{\left| A \right|}}\left( {adj A} \right)\].
Then,
\[{A^{ - 1}} = \dfrac{1}{{ - 1}}\left[ {\begin{array}{*{20}{c}}0&0&{ - 1}\\0&{ - 1}&0\\{ - 1}&0&0\end{array}} \right]\]
\[ \Rightarrow {A^{ - 1}} = \left[ {\begin{array}{*{20}{c}}0&0&1\\0&1&0\\1&0&0\end{array}} \right]\]
\[ \Rightarrow {A^{ - 1}} = A\]
Hence the correct option is D.
Note: If the determinant of a matrix is 0, then \[\dfrac{1}{{det A}}\] is undefined. So, the matrix with a 0 determinant has no inverse.
While calculating the inverse matrix, first check whether the determinant is nonzero or not.
Formula used:
The determinant of a \[3 \times 3\] matrix \[A = \left[ {\begin{array}{*{20}{c}}{{a_{11}}}&{{a_{12}}}&{{a_{13}}}\\{{a_{21}}}&{{a_{22}}}&{{a_{23}}}\\{{a_{31}}}&{{a_{32}}}&{{a_{33}}}\end{array}} \right]\] is: \[\left| A \right| = {a_{11}}\left( {{a_{22}}{a_{33}} - {a_{32}}{a_{23}}} \right) - {a_{12}}\left( {{a_{21}}{a_{33}} - {a_{31}}{a_{23}}} \right) + {a_{13}}\left( {{a_{21}}{a_{32}} - {a_{31}}{a_{22}}} \right)\]
The inverse matrix of a non-singular matrix \[A\] is: \[{A^{ - 1}} = \dfrac{1}{{\left| A \right|}}\left( {adj A} \right)\]
Complete step by step solution:
The given matrix is \[A = \left[ {\begin{array}{*{20}{c}}0&0&1\\0&1&0\\1&0&0\end{array}} \right]\].
Let’s calculate the determinant of the given matrix.
Apply the formula of the determinant of a \[3 \times 3\] matrix.
We get,
\[\left| A \right| = 0\left( {0 - 0} \right) - 0\left( {0 - 0} \right) + 1\left( {0 - 1} \right)\]
\[ \Rightarrow \left| A \right| = - 1\] \[.....\left( 1 \right)\]
Now calculate the adjoint matrix of the given matrix by using the co-factor method.
Let’s calculate the co-factors of the matrix.
\[{A_{11}} ={\left( { - 1} \right)^{1 + 1}}\left[ {\begin{array}{*{20}{c}}1&0\\0&0\end{array}} \right]
= {\left( { - 1} \right)^{1 + 1}}\left( {1 \times 0 - 0 \times 0} \right) = 0\]
\[{A_{12}} =\left[ {\begin{array}{*{20}{c}}0&0\\1&0\end{array}} \right]
= {\left( { - 1} \right)^{1 + 3}}{\left( { - 1} \right)^{1 + 2}}\left( {0 \times 0 - 1 \times 0} \right) = 0\]
\[{A_{13}} ={\left( { - 1} \right)^{1 + 3}}\left[ {\begin{array}{*{20}{c}}0&1\\1&0\end{array}} \right]
= {\left( { - 1} \right)^{1 + 3}}\left( {0 \times 0 - 1 \times 1} \right) = - 1\]
\[{A_{21}} ={\left( { - 1} \right)^{2 + 1}}\left[ {\begin{array}{*{20}{c}}0&1\\0&0\end{array}} \right]
= {\left( { - 1} \right)^{2 + 1}}\left( {0 \times 0 - 0 \times 1} \right) = 0\]
\[{A_{22}} ={\left( { - 1} \right)^{2 + 2}} \left[ {\begin{array}{*{20}{c}}0&1\\1&0\end{array}} \right]
={\left( { - 1} \right)^{2 + 2}}\left( {0 \times 0 - 1 \times 1} \right) = - 1\]
\[{A_{23}} ={\left( { - 1} \right)^{2 + 3}}\left[ {\begin{array}{*{20}{c}}0&0\\1&0\end{array}} \right]
= {\left( { - 1} \right)^{2 + 3}}\left( {0 \times 0 - 1 \times 0} \right) = 0\]
\[{A_{31}} ={\left( { - 1} \right)^{3 + 1}}\left[ {\begin{array}{*{20}{c}}0&1\\1&0\end{array}} \right]
= {\left( { - 1} \right)^{3 + 1}}\left( {0 \times 0 - 1 \times 1} \right) = - 1\]
\[{A_{32}} ={\left( { - 1} \right)^{3 + 2}} \left[ {\begin{array}{*{20}{c}}0&1\\0&0\end{array}} \right] ={\left( { - 1} \right)^{3 + 2}}\left( {0 \times 0 - 1 \times 0} \right) = 0\]
\[{A_{33}} = {\left( { - 1} \right)^{3 + 3}}\left[ {\begin{array}{*{20}{c}}0&0\\0&1\end{array}} \right]= {\left( { - 1} \right)^{3 + 3}}\left( {0 \times 1 - 0 \times 0} \right) = 0\]
So, the co-factor matrix of the given matrix is \[\left[ {\begin{array}{*{20}{c}}0&0&{ - 1}\\0&{ - 1}&0\\{ - 1}&0&0\end{array}} \right]\].
We know that the cofactor matrix is the transpose of the adjoint matrix.
So, the adjoint matrix of the given matrix is,
\[adj A = \left[ {\begin{array}{*{20}{c}}0&0&{ - 1}\\0&{ - 1}&0\\{ - 1}&0&0\end{array}} \right]\] \[.....\left( 2 \right)\]
Substitute the equations \[\left( 1 \right)\] and \[\left( 2 \right)\] in the formula of the inverse matrix \[{A^{ - 1}} = \dfrac{1}{{\left| A \right|}}\left( {adj A} \right)\].
Then,
\[{A^{ - 1}} = \dfrac{1}{{ - 1}}\left[ {\begin{array}{*{20}{c}}0&0&{ - 1}\\0&{ - 1}&0\\{ - 1}&0&0\end{array}} \right]\]
\[ \Rightarrow {A^{ - 1}} = \left[ {\begin{array}{*{20}{c}}0&0&1\\0&1&0\\1&0&0\end{array}} \right]\]
\[ \Rightarrow {A^{ - 1}} = A\]
Hence the correct option is D.
Note: If the determinant of a matrix is 0, then \[\dfrac{1}{{det A}}\] is undefined. So, the matrix with a 0 determinant has no inverse.
While calculating the inverse matrix, first check whether the determinant is nonzero or not.
Recently Updated Pages
Carbohydrates Class 12 Important Questions JEE Advanced Chemistry [PDF]

Crack JEE Advanced 2026 with Vedantu's Live Classes

JEE Advanced 2027 Revision Notes for Amino Acids and Peptides - Free PDF Download

JEE Advanced 2027 Revision Notes for Chemical Equilibrium - Free PDF Download

Solutions Class 12 Notes JEE Advanced Chemistry [PDF]

JEE Advanced 2022 Maths Question Paper 2 with Solutions

Trending doubts
JEE Advanced Percentile vs Marks 2026: JEE Main Cutoff, AIR & IIT Admission Guide

JEE Advanced 2026 Notification Out with Exam Date, Registration (Extended), Syllabus and More

JEE Advanced Weightage Chapter Wise 2026 for Physics, Chemistry, and Mathematics

Electrochemistry JEE Advanced 2027 Notes - Free PDF Download (Sign-in Required)

IIT CSE Cutoff 2026: Opening and Closing Ranks for B.Tech. Computer Science Admissions at All IITs

IIT Fees Structure for BTech Courses 2026: Complete Details

Other Pages
JEE Main 2026: Exam Dates, Session 2 Updates, City Slip, Admit Card & Latest News

Understanding the Electric Field of a Uniformly Charged Ring

Understanding Atomic Structure for Beginners

Electron Gain Enthalpy and Electron Affinity Explained

Derivation of Equation of Trajectory Explained for Students

How to Convert a Galvanometer into an Ammeter or Voltmeter

