I am having trouble solving matrices i understand the origin I think but I am having trouble preforming the correct row operations and also what all row operations I can preform. Is there anyone who can help me?

Question

anonymous · Answer

DanielxAK can help you.

anonymous · Answer

By origin, do you mean the identity of a matrix?

Assuming you're trying to reduce the matrix, these are the row operations allowed:

* Switch one row with another row
* Divide/Multiply an entire row by a number
* Take one row and add it to another row

You can combine the third one with the second one also. So, I can take 2 times a row and add it to a different row, for example.

anonymous · Answer

I have to take it all the way down to reduced row echelon form. I am getting confused when trying to preform different row operations. Also getting stuck. Can I add row one and row 2 to get row 3?

anonymous · Answer

There's no reason to do that. You want to go row by row getting your pivot columns. So, start with row 1, and get the leading term a 1. Then, add row 1 times some number to get 0 for the first number in row 2. Do this for all the rows. So, you'd have something like:

[x x x
 x x x 
 x x x]

=>

[x x x 
 0 x x 
 x x x]

=> 

[ x x x
  0 x x
  0 x x]

Then, start with row 2 and do the same thing, so you'd now have:

[x x x
0 x x
0 0 x]

anonymous · Answer

[1 -2 3/7
  2  1  1/4
 -3 2  -2/10] so I multiplied row 1 by 2 then subtracted it from row 1 to get this new row 2. -   [0 -5 -7/-18]

anonymous · Answer

now I I did r3+3r1=R3

anonymous · Answer

[0 -4 7/11]

anonymous · Answer

Is this correct?

anonymous · Answer

Close. You should have 31 instead of 11, unless you meant -10 in your original problem.

anonymous · Answer

sorry I meant -10 in the original!

anonymous · Answer

Ah okay. Then, yes. Correct.

anonymous · Answer

now I did -1)r3+r2=R2 that gave me [0 -1 0/-29] so i then multiplied that by -1 is that legal?

anonymous · Answer

but i still have [0 -4 7/11] for r3 do i have to have the form 
x x x
0 x x
0 0 x first?

anonymous · Answer

You don't have to. It's just conventional to do it that way.

Also, be careful. You should have [ 0 1 0 7] (or [0 -1 0 -7]) for R2. Make sure you watch your signs.