how to get the equation of the plane. [read this one]

[UNIQNESS]

http://www.isquaredonline.com/chips/1.jpg

the above link is the answer to the problem i'm solving. i was wondering how i'd come up with the equation of the plane "x-y+z=0" when only the vertices of the plane are provided in the problem. thanks in advance.

[Galileo]

The equation of a plane through the origin is always of the form ax+by+cz=0.
Now you can plug in some points. Say, put in (1,1,0) and you'll find a=-b.
Putting in (0,1,1) b=-c. So the equation reduces to ax-ay+az=0 or x-y+z=0.

[UNIQNESS]

thanks for the help.