Question 1207192
<br>
{{{2x-3y-9z=20}}} [1]
{{{x+3z=-2}}} [2]
{{{-3x+y-4z=-2}}} [3]<br>
The instructions are to write x and y as functions of z.  We can get x as a function of z directly from [2]:<br>
{{{x=-3z-2}}} [4]<br>
Substitute [4] in [1] and solve to find y as a function of z:<br>
{{{2(-3z-2)-3y-9z=20}}}
{{{-6z-4-3y-9z=20}}}
{{{-3y-15z=24}}}
{{{y+5z=-8}}}
{{{y=-5z-8}}} [5]<br>
ANSWER:
z = z
x = -3z-2
y = -5z-8<br>