Eliminate the “z” variable in the last two equations by finding opposite coefficients and adding. What is the resulting equation?

x + 3y + 2z = –16
2x – y + 2z = –15
2x – 2y – z = 1
Answer 6x – 5y = –13
4x – 3y = –14
6x + 5y = 13
4x + y = –14

Question

Eliminate the “z” variable in the last two equations by finding opposite coefficients and adding. What is the resulting equation?

x + 3y + 2z = –16
2x – y + 2z = –15
2x – 2y – z = 1
Answer    6x – 5y = –13 
   4x – 3y = –14 
   6x + 5y = 13 
   4x + y = –14

anonymous · Answer

Last two equations are
2x – y + 2z = –15  <---- Here coefficient of z is +2 and its opposite is -2
2x – 2y – z = 1     <----- If we multiply this equation by 2, then -z becomes -2z
so then we get
2x –   y + 2z = –15
4x – 4y – 2z = 2      Now on adding the two we get..
6x - 5y = -13
so answer is the first choice  6x – 5y = –13