Check sibling questions

Ex 3.4, 5 - Chapter 3 Class 12 Matrices (Term 1)

Last updated at Dec. 8, 2016 by

Ex 3.4, 5 - Find inverse [2 1 7 4] - Chapter 3 Class 12 - Ex 3.4

Ex 3.4, 5 - Chapter 3 Class 12 Matrices - Part 2
Ex 3.4, 5 - Chapter 3 Class 12 Matrices - Part 3

Solve all your doubts with Teachoo Black (new monthly pack available now!)

Join Teachoo Black

Transcript

Ex3.4, 5 Find the inverse of each of the matrices, if it exists. [ 8(2&1@7&4)] Let A = [ 8(2&1@7&4)] We know that A = IA [ 8(2&1@7&4)] = [ 8(1&0@0" " &1)] A R1 R1 1/7 R2 [ 8( / ( )&1 1/7(4)@7&4)] = [ 8(1 1/7(0)&0 1/7(1)@0" " &1)] A [ 8( &1 4/7@7&4)] = [ 8(1 0&( 1)/7@0" " &1)] A [ 8( &3/7@7&4)] = [ 8(1&( 1)/7@0" " &1)] A R2 R2 7R1 [ 8(1&3/7@ ( )&4 7(3/7) )] = [ 8(1&( 1)/7@0 7(1)&1 7(( 1)/7) )] A [ 8(1&3/7@ &4 3)] = [ 8(1&( 1)/7@0 7&1+1)] A [ 8(1&3/7@ &1)] = [ 8(1&( 1)/7@ 7&2)] A R1 R1 3/7R2 [ 8(1 3/7(0)& / / ( )@0&1)] = [ 8(1 3/7( 7)&( 1)/7 3/7(2)@ 7&2)] A [ 8(1 0& / / @0&1)] = [ 8(1+3&( 1)/7 6/7@ 7&2)] A [ 8(1& @0&1)] = [ 8(4& 1@ 7" " &2)] A I = [ 8(4& 1@ 7" " &2)] A This is similar to I = A-1A Thus, A-1 = [ 8(4& 1@ 7" " &2)] A

Davneet Singh's photo - Co-founder, Teachoo

Made by

Davneet Singh

Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 12 years. He provides courses for Maths, Science, Social Science, Physics, Chemistry, Computer Science at Teachoo.