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

A) 4x - 3y = -14
B) 4x + y = -14
C) 6x + 5y = 13
D) 6x - 5y = -13

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 


A) 4x - 3y = -14 
B) 4x + y = -14 
C) 6x + 5y = 13 
D) 6x - 5y = -13

whpalmer4 · Answer

The last two equations:
$$2x-y+2z=-15$$$$2x-2y-z=1$$
Well, the coefficients of $z$ are opposite in sign as desired, but not equal in magnitude (+2 vs -1).  What would be the easiest way to get them to be both opposite sign and equal in magnitude (for example, +2, -2)?