SOLUTION: I do not understand this: Solve the following system of equations: 2x+3y-x=0 X-2y-4z=14 3x+y-8z=17 This is all one problem.I'm having trouble and need some guidance if you

Algebra ->  College  -> Linear Algebra -> SOLUTION: I do not understand this: Solve the following system of equations: 2x+3y-x=0 X-2y-4z=14 3x+y-8z=17 This is all one problem.I'm having trouble and need some guidance if you      Log On


   

Question 1047631: I do not understand this:
Solve the following system of equations:
2x+3y-x=0
X-2y-4z=14
3x+y-8z=17
This is all one problem.I'm having trouble and need some guidance if you could please to make this a little more simple for me to understand. Thank you so much for you time and help.
Found 2 solutions by ikleyn, stanbon:
Answer by ikleyn(52781) About Me  (Show Source):
You can put this solution on YOUR website!
.
I suspect that your first equation is written incorrectly.
Check it. Fix it, if necessary.
Then re-submit.


Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
Solve the following system of equations:
2x+3y-x=0
X-2y-4z=14
3x+y-8z=17
Interchange row 1 and row 2 to get:
-------------------
X-2y-4z=14
2x+3y-x=0
3x+y-8z=17
Subtract 2*row 1 from row 2
Subtract 3*row 1 from row 3
----------------------
x - 2y - 4z = 14
0 + 7y +7z = -28
0 + 7y -5z = 17
---------------------------
Subtract row 2 from row 3 to get:
x - 2y - 4z = 14
0 + 7y + 7z = -28
0 + 0 -12z = 45
-------------------------
Solve row 3 for "z"
z = -15/4
------
Divide thru row 2 by 7 to get::
x - 2y - 4z = 14
0 + y + z = -4
-----------------------------
Substitute for "z" and solve for "y"::
x - 2y - 4z = 14
y = -4+15/4
y = -1/4
---------------------
Substitute for y and z in row 1 and solve for "x":
x - 2(-1/4) - 4(-15/4) = 14
-------------------
x + (1/2) + 15 = 14
x = -3/2
---------------------
Cheers,
Stan H.
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