Question

Help please...
system with 3 variables
3x+2y-z=12
-4x+y-2z=4
x-3y+z= -4

Answer 1

@jim_thompson5910

Answer 2

what methods do you know

Answer 3

like trying to eliminate 1 of the variables

Answer 4

ok, if you add equations 1 and 3, what do you get

Answer 5

4x-1y+8

Answer 6

you mean 4x-y = 8 right?

Answer 7

yes

Answer 8

x= -2
y= 6
z= -6

Answer 9

now double everything in equation 3 to go from

x-3y+z= -4

to

2x-6y+2z= -8


Then add this to equation 2

What do you get?

Answer 10

wait i don't understand double everything, what do you mean

Answer 11

multiply everything in equation 3 by 2

Answer 12

ok and i got 2x-6y+2z= -8

Answer 13

now add this to equation 2

Answer 14

i got -2x-5y= -4

Answer 15

what would i do next, cause it looks confusing now

Answer 16

ok, you now have these 2 equations

Answer 17

4x-y = 8
-2x-5y = -4

Answer 18

focus on them only and forget about the rest for now

Answer 19

ok i got 2x-6y=4

Answer 20

multiply everything in equation 1 by -5

4x-y = 8

-5*4x+(-5)*(-y) = -5*8

-20x + 5y = -40

Now add -20x + 5y = -40 to -2x-5y = -4

Answer 21

ok am confused but i got so far is -40x= -44

Answer 22

-20x + 5y = -40
-2x-5y = -4
------------------
-22x = -44


-22x = -44

x = -44/(-22)

x = 2

Now use this to find y

Answer 23

ok and then i'd plug it in a equation

Answer 24

yes

Answer 25

either

-20x + 5y = -40

or

-2x-5y = -4

or

4x-y = 8

Answer 26

ok and am sorry but how did you get 4x-y=8

Answer 27

it was the result when we added the 1st and 3rd equations (in the very beginning)

Answer 28

ok thanks i kinda understand it now just some parts idk still kinda like confusing

Answer 29

go over them again and hopefully they'll make more sense (try to reword them if they still don't)

Answer 30

ok i will and thanks alot though :) oh y=0, z=-6 right

Answer 31

that is correct

Answer 32

ok thanks