Question 860688
1.{{{x+2y-3z=2}}}
2.{{{3x-z=-8}}}
3.{{{2x-3y+5z=-9}}}
from Eq. 2,
{{{z=3x+8}}}
Substitute into eqs. 1 and 3,
{{{x+2y-3(3x+8)=2}}}
{{{x+2y-3x-12=2}}}
{{{-2x+2y=14}}}
4.{{{-x+y=7}}}
.
.
{{{2x-3y+5(3x+8)=-9}}}
{{{2x-3y+15x+40=-9}}}
5.{{{17x-3y=-49}}}
Multiply eq. 4 by 3 and add to eq. 5,
{{{-3x+3y+17x-3y=21-49}}}
{{{14x=-28}}}
{{{x=-2}}}
Now work backwards,
From eq. 4,
{{{-(-2)+y=7}}}
{{{2+y=7}}}
{{{y=5}}}
and finally,
{{{z=3(-2)+8}}}
{{{z=2}}}