# Finding Inverse (confused) help Asap

#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

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Hurkyl
Staff Emeritus
Gold Member
What's confusing?

how to do the actual inverses....when it comes to the Gauss-Jordan method...i get lost

these problems are due by 2 tomm

Hurkyl
Staff Emeritus
Gold Member
Well, where do you get lost?

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....

Hurkyl
Staff Emeritus
Gold Member
Why are you talking about equations? When doing Gaussian elimination, you do nothing but row operations a matrices.

thats what i am refering to...

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)