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 1

multiple the last equation by 2 and add it to the second equation

Answer 2

I have a question though, how did you know how to do that? Why multiply it by 2?

Answer 3

So that the coefficients of z match up to give 0 when added.

Answer 4

notice that the z variable in the second equation is +2z, now notice that the z variable in the last equation is -z. If we are going to add we need to multiply that -z by a number so that when we add it to +2z it will give us zero

Answer 5

2*-z is -2x. If we add -2z+2x we get 0

Answer 6

I get it now.(: Thank you so much. (:

Answer 7

thats right, you just got schooled