Posted by **Darren** on Tuesday, June 1, 2010 at 8:28pm.

Could someone help me solve these system using elementary operations, I am having trouble with both of them.

x+y+z =0

x-y =1

y-z =-5

(For the one above the answer is (-1,-2,3)

2x-y =0

2y-z =7

2z-x =0

(For the one above the answer is (2,4,1)

- Vectors -
**Reiny**, Tuesday, June 1, 2010 at 9:09pm
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(4x-7) - x = 0

7x = 14

x = 2

Now you can find the other two.

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