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**maths_buff****Member**- Registered: 2005-05-26
- Posts: 14

How would I plot linear equations with three variables?

Here's my own problem:

x + y + z = 6

2x - 3y + 4z = 4

x + 2y - z = 6

In this problem I made, x = 3, y = 2 and z = 1

I have tried downloading some programs but they keep saying my syntax is wrong.

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**Milos****Member**- Registered: 2005-05-06
- Posts: 44

You have a system of 3 equations here:

From the first one find x, it is

x=6-y-z

put it in the second one:

2(6-y-z)-3y+4z=4

12-2y-2z-3y+4z=4

-5y=-8-2z /*(-1)

5y=8+2z

y=(8+2z)/5

Now put x, y in the third one:

6-(8+2z)/5-z+(16+4z)/5-z=6

6+(8+2z)/5-2z=6

(8+2z)/5=2z /*5

8z=8

z=1

than:y=(8+2)/5=2

and:x=6-2-1=3

There are some other ways to do it- shorter ones :). If you are interested, I can show you.

*Last edited by Milos (2005-05-26 23:42:11)*

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**maths_buff****Member**- Registered: 2005-05-26
- Posts: 14

I think you may have misunderstood me, Milos. I know what x, y and z; I'm looking on how to plot/graph them.

Notice how I said x = 3, y = 2 and z = 1 in my first post?

Cheers,

Kris

*Last edited by maths_buff (2005-05-26 23:45:56)*

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**Milos****Member**- Registered: 2005-05-06
- Posts: 44

ups . My apologies

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