• Support PF! Buy your school textbooks, materials and every day products Here!

Finding Inverse (confused) help Asap

  • Thread starter CRTNY
  • Start date
  • #1
5
0
#1)2 4
6 -4

#2) 1 4
-2 -8

#3) 3 1
0 2

#4) 1 5 6
2 1 1
0 -4 -8
 

Answers and Replies

  • #2
Hurkyl
Staff Emeritus
Science Advisor
Gold Member
14,916
18
What's confusing?
 
  • #3
5
0
how to do the actual inverses....when it comes to the Gauss-Jordan method...i get lost
 
  • #4
5
0
these problems are due by 2 tomm
 
  • #5
Hurkyl
Staff Emeritus
Science Advisor
Gold Member
14,916
18
Well, where do you get lost?
 
  • #6
5
0
once you set up the equation (for example #1) to 2x+4z=1
6x+-4=0

and go on to set up 2 4| 1 0
6 -4| 0 1

...I don't know what to do from here...this step is where the Gauss-Jordan method comes in...and I don't know how to set up the Row equation....
 
  • #7
Hurkyl
Staff Emeritus
Science Advisor
Gold Member
14,916
18
Why are you talking about equations? When doing Gaussian elimination, you do nothing but row operations a matrices.
 
  • #8
5
0
thats what i am refering to...
 
  • #9
173
0
When doing GJ the method is to make the first row, first column a 1, and then 0's in the rest of the rows in that column. Since there is a 2 in R1 C1, you would take 1/2 R1 to make the two a one. Then you have to make the 6 a 0, so you would go: R2 - 6R1 (to get rid of the 6)

Now your matrix is:

1 2 | 1/2 0
0 -10 | -3 1

or something like that. Now make the -10 a 1 and make the two a 0 after that. Then the right hand side will be your inverse. There is an easier way of finding inverses for a 2x2 matrix using inverses though.
 

Related Threads on Finding Inverse (confused) help Asap

  • Last Post
Replies
5
Views
970
  • Last Post
Replies
2
Views
2K
Replies
3
Views
3K
Replies
0
Views
1K
Replies
5
Views
879
  • Last Post
Replies
1
Views
2K
  • Last Post
Replies
8
Views
1K
  • Last Post
Replies
2
Views
1K
  • Last Post
Replies
3
Views
1K
  • Last Post
Replies
2
Views
662
Top