Question 168727
4x+y-z=7
-2x+2y+5z=3
7x-3y-9z=-4
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x = -1
y = 8
z = -3
I have an Excel sheet that does these. If you have Excel and want a copy, email me.

Doing them by hand is tedious and error prone.  It's important to know how to do them, but once you know, it's better to avoid it.