Answer :
To eliminate a term, its coefficients in both equations must be opposite numbers.
[tex]x+z=6 \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ |\times (-2) \\ 3x+2z=1 \\ \\ -2x-2z=-12 \\ \underline{3x+2z=1 \ \ \ \ \ \ \ \ } \\ x=-11 \\ \\ x+z=6 \\ -11+z=6 \\ z=6+11 \\ z=17 \\ \\ (x,y)=(-11,17)[/tex]
The answer is A. multiply equation A by -2.
[tex]x+z=6 \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ |\times (-2) \\ 3x+2z=1 \\ \\ -2x-2z=-12 \\ \underline{3x+2z=1 \ \ \ \ \ \ \ \ } \\ x=-11 \\ \\ x+z=6 \\ -11+z=6 \\ z=6+11 \\ z=17 \\ \\ (x,y)=(-11,17)[/tex]
The answer is A. multiply equation A by -2.