Posted by Darren on .
Could someone help me solve these system using elementary operations, I am having trouble with both of them.
x+y+z =0
xy =1
yz =5
(For the one above the answer is (1,2,3)
2xy =0
2yz =7
2zx =0
(For the one above the answer is (2,4,1)

Vectors 
Reiny,
first one:
add all 3 equations > 2x + y = 4
now add this to the second ...
3x = 3
x = 1
sub that onto the second and third to get y and z
"play around" with the second question in a similar way.
I would use substitution,
e.g. for the first > y = 2x
from the second z = 2y  7
z = 2(2x)  7
= 4x  7
now in the third
2z  x = 0
2(4x7)  x = 0
7x = 14
x = 2
Now you can find the other two.