Browse by Stream
QnA
Home
QnA
Go To Your Study Dashboard

Get Answers to all your Questions

header-bg qa
  • Home
  • School
  • please solve rd sharma class 12 chapter adjoint and inverse of a matrix exercise multiple choice questions question 8 maths textbook solution

please solve rd sharma class 12 chapter adjoint and inverse of a matrix exercise multiple choice questions question 8 maths textbook solution

Answers (1)

:  option (a) 144   

Given: A= \begin{bmatrix} 1& 2 & -1 \\ -1& 1& 2\\ 2& -1& 1 \end{bmatrix}

Hint: calculate adjoint of A and put the value in it.

Solution:
\begin{aligned} &A=\left[\begin{array}{ccc} 1 & 2 & -1 \\ -1 & 1 & 2 \\ 2 & -1 & 1 \end{array}\right] \\ &|A|=1(1+2)-2(-1-4)-1(1-2) \\ &=3+10+1=14 \\ &|A| \neq 0 \\ &\Rightarrow \operatorname{adj}(\operatorname{adj} A)=|A|^{(n-1)^{2}} \mid \end{aligned} 

Where n=3 because of 3×3 matrices 

\begin{aligned} &=|A|^{(3-1)^{2}} \\ &=|A|^{2^{2}} \\ &=|A|^{4} \\ &=14^{4} \quad(\therefore|\mathrm{A}|=14) \\ \end{aligned}

Hence, option (a) is correct.

 

Posted by

Info Expert 29

View full answer

Crack CUET with india's "Best Teachers"

  • HD Video Lectures
  • Unlimited Mock Tests
  • Faculty Support
cuet_ads

Similar Questions

Trending Articles/News

anam-khan

PM Modi's Pariksha Pe Charcha 2025 to be held next month, registrations open till January 14
anam-khan

CBSE Board Exams 2025: Online portal for availing exemptions by CWSN students opens
anam-khan

Board Exams: States agree to equivalence; no question paper ‘jumbling’ from next year, says PARAKH CEO

Latest Question