The following system is solved by substitution. Which expression is substituted for z in the second and third equations?

x + 4y + z = -10
3x - 3y + 6z = -21
x + 2y + 2z = -10

a. x + 4y - 10
b. -x + 4y - 10
c. -x - 4y - 10
d. x - 4y - 10

Question

The following system is solved by substitution. Which expression is substituted for z in the second and third equations?

x + 4y + z = -10
3x - 3y + 6z = -21
x + 2y + 2z = -10

a. x + 4y - 10 	
b. -x + 4y - 10 	
c. -x - 4y - 10 	
d. x - 4y - 10

terenzreignz · Answer

One of the more basic-skills in algebra is solving for a particular variable.
If you're going to replace the z in the second and third equations, it has to have been the z-value in the first equation:
x + 4y + z = -10
Can you solve for z here?