Answer:
(x, y, z) = (-4, 29, 17)
Step-by-step explanation:
These three equations have a unique solution. If you want "z arbitrary", you need to write a system of two equations with three variables (or, equivalently, a set of dependent equations).
It is convenient to let a graphing calculator, scientific calculator, or web site solve these.
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You can reduce the system to two equations in y and z by ...
subtracting the last equation from the first:
3y -7z = -32
subtracting twice the last equation from the second:
3y -2z = 53
Subtracting the first of these from the second, you get ...
5z = 85
z = 17
The remaining variable values fall out:
y = (53+2z)/3 = 87/3 = 29
x = -9 +2z -y = -9 +2(17) -29 = -4
These equations have the solution (x, y, z) = (-4, 29, 17).
