I know the answer has to have 8x+4y=16 but I don't know how to figure the second one out
If you were to use the elimination method to solve the following system, choose the new system of equations that would result after the variable z is eliminated in the first and third equations, then the second and third equations.

5x + 3y – 2z = 16
8x + y – 2z = 8
3x + y + 2z = 0

5x + 3y = 16
11x + 2y = 8

8x + 4y = 16
3x + y = 0

8x + 4y = 16
11x + 2y = 8

5x + 3y = 16
3x + y = 0

Question

I know the answer has to have 8x+4y=16 but I don't know how to figure the second one out
If you were to use the elimination method to solve the following system, choose the new system of equations that would result after the variable z is eliminated in the first and third equations, then the second and third equations. 

5x + 3y – 2z = 16 
8x + y – 2z = 8 
3x + y + 2z = 0 

 5x + 3y = 16 
11x + 2y = 8 

 8x + 4y = 16 
3x + y = 0 

 8x + 4y = 16 
11x + 2y = 8 

 5x + 3y = 16 
3x + y = 0

primeralph · Answer

What's "the second one"?

psymon · Answer

You can just add the first and 3rd equations right off the bat and eliminate z in those particular equations. Since that's all it is asking.

anonymous · Answer

I did that and I got 5x+2y=8 and that isn't an option

psymon · Answer

8x + 4y would be the first one. 

5x + 3y - 2z
3x + y + 2z

anonymous · Answer

yeah I got that

psymon · Answer

And then for the 2nd and 3rd ones you get
8x + y - 2z
3x + y + 2z   = 11x + 2y  for the 2nd question

anonymous · Answer

ohh I subtracted instead of added

psymon · Answer

Simple mistake at least. I rather see that than a complete concept misunderstanding.

psymon · Answer

Always assume add though for these. You may have negative numbers, but even then, just think of it as a minus + a minus.