Posted by T.Gracken on November 06, 2002 at 19:16:16:
In Reply to: solving a 3 variable system posted by Sarah on November 06, 2002 at 18:54:35:
: Can someone please explain in simple term how to solve a 3 variable system
: ex.
: 2x+y+z=8
: x+2y-z=-5
: z=2x+y
: Please help!!!!!!
it is amazing that everyone wants a "simple expanation". it doesn't always happen... deal with it!
but, for your problem... since you know z = 2x+y (last equation), substitue 2x+y for z in the first two equations and you have
2x + y + (2x+y) = 8
and
x + 2y - (2x+y) = -5
is that simple enough to start?
if not (i quit...). if so then simplify the two equations to get
4x + 2y = 8 ..(which is the same as 2x + y = 4)
and
-x + y = -5
Now solve this (2x2 system)
do it!!!