Question 843225
Are there no z components in the 2nd and third equations?
{{{(matrix(3,3,2,-1,1,1,-1,0,0,1,0))*(matrix(3,1,x,y,z))=(matrix(3,1,5,-30,9))}}}
If not, equations 2 and 3 make the system inconsistent. 
IF there was an error in your equations, please repost.