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)

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)

anonymous · Answer

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

anonymous · Answer

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

anonymous · Answer

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