The question is " Find the inverse of the following matrices by using transformation method " What i want to - Maths -

Question

The question is " Find the inverse of the following matrices by
using transformation method?"
What i want to know is in the circled part after i substitute the
values how does 13 come and why does 3 stay the same?
Method A

A = 1           3 a - 1 A A - 1 = 1 R 1
            3 4      
  - 1 A - 1     1          
  0 0             1 R 2 →
R 2 - 4 R 1 1             3 0  
        - 13 A - 1   = 1    
        0 - 4        
    1

Ashutosh Verma · Accepted Answer

Please find below the solution to the asked query:

First of all do not get confuse between row and column Here ,

Rows : R1 = [ 1 3 ] , R2 = [ 4 - 1 ]

And

Column : C1 = 14 and C2 = 3- 1

And when we apply : R2 = R2 - 4 R1
, So

We get : 4 R1 = 4 [ 1 3 ] = [ 4 , 12 ]

And

R2 - 4 R1 = [ 4 - 1 ] - [ 4 , 12 ] = [ 4 - 4
- 1 - 12 ] = [ 0 - 13 ]

Hope this information will clear your doubts about topic