Question

2x+4y-z=7
2x-4y+2z=-6
x+4y+z=0

Answer 1

assum first with second
2x+4y-z=7
2x-4y+2z=-6
---------------
4x 0 +z=1

and assum second with 3rd

2x-4y+2z=-6
x+4y+z =0
--------------
3x+ 0 3z=-6

4x+z=1 multiply by -3
3x+3z=-6

-12x-3z=-3
3x+3z=-6
------------- assum
-9x 0 =-9
-9x=-9
x= -9/(-9) =1
x=1

4(1)+z=1 so 4+z=1 so z=-3

x+4y+z=0
1+4y-3=0
4y=2
y=2/4 = 1/2

x=1
y=1/2
z=-3