# Thread: Cant solve another matrix, need hel

1. ## Cant solve another matrix, need hel

{ 30 10 20 | 340
10 10 20 | 180
10 30 20 | 220 }

I need to solve this matrix using Gauss-Jordan, but i am completely clueless, i would greatly appreciate help, thanks.

2. Originally Posted by burdonjo
I need to solve this matrix using Gauss-Jordan, but i am completely clueless.
Then the first thing you'll need to do is study some lessons on the topic. Try here.

Once you have learned the basics, please attempt the exercise. If you get stuck, you will then be able to reply with a clear listing of your work and reasoning so far, at which point we'll be able to "see" where you're having trouble, and provide assistance.

Thank you!

3. You could also study the complete worked solution you were given in another recent thread on the same topic.

4. ## Still having trouble

I can only figure out pretty much 2 by 2 matrices or solve the problems on the calculator (rref), but i am just really stuck on this problem, I am sorry to bother you guys, i am just really stressing out over this problem.

5. ## Cant get past two steps, im stuck

After taking 1/20 to R3, and 1/30 to R1, I am stuck. I probably already screwed the problem up.

6. did you divide every element in the matrix by 10 to make calculations easier?

7. ## Dividing by 10

I originally tried to solve the matrix as is..... and did not to very well, so i tried dividing everything by 10, and still after two or three steps i somehow manage to screw up the problem miserably

8. I've tried it three more times and still can't figure it out man..... I'm falling apart on this problem

9. 30 10 20 | 340
10 10 20 | 180
10 30 20 | 220

first to make your life simpler follow skeeter's suggestion to divide the whole matrix by 10. (This is scalar multiplication by 1/10 so we can do this without changing the meaning of the matrix).

3 1 2 | 34
1 1 2 | 18
1 3 2 | 22

now you can proceed by doing something like taking the 2nd row and subtracting the 3rd row from it.

3 1 2 | 34
0 -2 0 | -4
1 3 2 | 22

and so on and so on.

10. Originally Posted by Demagodnewb
30 10 20 | 340
10 10 20 | 180
10 30 20 | 220

first to make your life simpler follow skeeter's suggestion to divide the whole matrix by 10. (This is scalar multiplication by 1/10 so we can do this without changing the meaning of the matrix).

3 1 2 | 34
1 1 2 | 18
1 3 2 | 22
I would be inclined to make my first step to swap the first and second rows. Then subtract 3 times the (new) first row form the second and subtract the (new) first row from the third to get:

1 1 2 | 18
0 -2 -4 | 20
0 2 0 | 4

now you can proceed by doing something like taking the 2nd row and subtracting the 3rd row from it.

3 1 2 | 34
0 -2 0 | -4
1 3 2 | 22

and so on and so on.