BOB48990
Oct 5, 2009, 03:23 PM
How do I solve system of equations in three variables? Ex: 2x+y-z=-8
4x-y+2z=-3
-3x+y+2z=5
Unknown008
Oct 6, 2009, 12:30 AM
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!
:)