Question

Solve the system by the method of substitution.

2x-2y-z=-14
z=-8
2x+3y+3z=-6

A. (3, 8, –8)

B. (–3, –8, –8)

C. (–3, 8, 8)

D. (–3, 8, –8)

Answer 1

first substitute z=-8 in the first and second equation and you will have 2 equations in 2 unknowns

Answer 2

You will get
\[
2 x - 2y =-22\\
2 x+ 3y =18

\]

Answer 3

the first equation gives
\[
x-y =-11\\
x= y -11
\]
Substitute x by its value to get\[
2(y-11) + 3y =18\\
2y -22 + 3y =18\\
5y =40\\
y=8\\
x= y-11=8-11=-3
\]
So it is D