How do I solve system of equations in three variables? Ex: 2x+y-z=-8
4x-y+2z=-3
-3x+y+2z=5

2x+y-z=-8

4x-y+2z=-3

-3x+y+2z=5

First, try making equations with two variables, which you'll then solve simultaneously.

For example:

2x+y-z=-8

2x+y+8=z ---a.

4x-y+2z=-3

Sub a in 2.

4x-y+2(2x+y+8)=-3

4x-y+4x + 2y + 16=-3

8x+y+19=0 ----b.

-3x+y+2z=5

Sub a in 3.

-3x+y+2(2x+y+8)=5

x+3y+11=0 ----c

now, solve b and c simultaneously!

:)