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
PLEASE HELP!

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
PLEASE HELP!

anonymous · Answer

if you are only trying to find z from the first equation you just substract x and 4y getting the expression of z=-10-x-4y
this way when you plug z in you can made the other two equations only two variable and easier to solve by subtraction

anonymous · Answer

Would this be the final answer: -x - 4y - 10? @insanitycat

anonymous · Answer

yes that would be the expression

anonymous · Answer

Thank you!