Question

Solve by sublimation. Can you just tell me what the first few steps are @myininaya?
-x-y-z=-8
-4x+4y+5z=7
2x+2z=4

Answer 1

sublimation wont help you solve that (sublimation is a chemistry turn, turning solid into gas skipping liquid phase)

Answer 2

chemistry term*

Answer 3

i think he just combine the words substitution and elimination
making a new word (or a new one for me at least) sublimation
But maybe it should be sublimination.

Answer 4

right, he meant elimination. but i thought it was still funny

Answer 5

Anyways...
You could try to eliminate the x variable getting two equations in terms of 2 variables y and z.

(I thought it was cute and funny too :p)

Answer 6

To start with:
Divide both sides of the third equation by 2.
Add the result above to the first equation. y = 6

Answer 7

or getting two equations in terms of z and x since the last one is in terms of just z and x but you can try rob's way too

Answer 8

Sorry! I meant substitution!

Answer 9

@myininaya I meant substitution :)

Answer 10

Ok so first last write your last equation as
x+z=2

Answer 11

now your first equation is -(x+z)-y=-8

Answer 12

right ?

Answer 13

umm...one second

Answer 14

I don't remember.....this is just confusing.....I'm used to doing 2 variables, not 3....:(

Answer 15

Ok I haven't done anything yet except rewrite your first and last equation

Answer 16

First equation is -(x+z)-y=-8
Last equation is x+z=2

Answer 17

okay :) why do we need to write the first one like that?

Answer 18

Do you see how you can sub the last equation into the first?

Answer 19

-put it in as -(2)-y=8

Answer 20

I wrote it like that so it easy for you to tell tat you can replace x+z with 2

Answer 21

yep

Answer 22

well -2-y=-8*

Answer 23

okay :) sorry so um y=6

Answer 24

yep

Answer 25

no how do I do the x and z?

Answer 26

now*

Answer 27

So remember we had these equations: \[x+z=2 \\ y=6 \\ -4x+4(6)+5z=7 \]
You can solve that first one for x
and then replace the x in the last equation with something in terms of z

Answer 28

with something...? what do you mean? OOHHHH!!!! so I can isolate z or x and plug it into a different equation! I get it now :P

Answer 29

right?

Answer 30

@myininaya?

Answer 31

yes

Answer 32

Well I mean to isolate x in the first equation
then take that x and replace in the last equation
this will give an equation in terms of z

Answer 33

okay :) thank you. I'm gonna plug it into the 1st one instead :) It seems easiest to isolate

Answer 34

either way

Answer 35

-4(2-z)+4(6)+5z=7?

Answer 36

Beautiful

Answer 37

So we have another equation just in terms of z

Answer 38

z=-1

Answer 39

-8+4z+24+5z=7
-8+9z+24=7
9z=15-24
9z=-9
ok yeah I see z=-1

Answer 40

x=3

Answer 41

checking:
z+x=2
-1+x=2

Answer 42

looks good

Answer 43

are you going to check your solution like you did last time?

Answer 44

yup

Answer 45

that's good practice :)

Answer 46

thanks :)