# Thread: System of linear equations.

1. ## System of linear equations.

Hi! This is my first post and hopefully someone will be able to help me! I have tried this problem atleast 10 times but I am just getting frustrated... it's not working! Here it is:

you have to solve for x, y, and z.. and I could get one but then it doesnt work for the other problems...

2x+y+z=4

3x-y+4z=11

x-y+5z=20

2. If you combine the first and second you can get $\displaystyle 5x+5z=15$.

If you combine the second and third you can get $\displaystyle 2x-z=-9$.

Can you solve that two variable system?

3. THANKS!I got :
x=2
z+1
y=-7

Am I correct?? HOW did you do that?! I have tried and tried with no luck.. at one point I thought x=4 so maybe I just needed to divide or something.. Maybe I'm not a lost cause after all! THANKS so much!

4. Thanks!

5. I think I got it now! I got a little excited before that you made progress and I missed the (-)! NOW this is what I got:

x= -2
y=3
z= 5

? Howd I do? THANKS so much! Sorry If im posting too much I'm just so glad to have this answer!

6. Correct. To see if you're correct, simply substitute your values
in one of the original equations; OK?

7. Thank you so much! VERY much appreciated!! If I may ask how long did it really take you to do that? I sat literally for 45 minutes trying to do it and no luck! But I did find that on my paper what Plato wrote so I need to pay more attention to the (-) and such. Thanks again!