Question

solve by substitution
help
y = x + 2
-x - 2y = 8

Answer 1

Cool, so what have you done so far?

Answer 2

nvm I got the problem but heres another one
-3x+y=-4
3x-3y=6
do I subtract 3x from -4?

Answer 3

post the question is what she's done

Answer 4

no. it says by substitution

Answer 5

yeah I know but to get y =

Answer 6

like y = -3x - 4?

Answer 7

substitute the first equation, that is y = x + 2 into the y of the second equation

Answer 8

y = x + 2 use this into
-x - 2(x+2) = 8 this

Answer 9

im talking about this problem lol
-3x+y=-4
3x-3y=6

Answer 10

So what you want to do is, isolate one of the variables x or y from one of the equations and substitute it into the second equation.

Answer 11

would that require substitution? maybe, but why make life difficult when you can just solve y immediately

Answer 12

The questions requires to use substitution

Answer 13

yes

Answer 14

So which one of the equations do you want to use?

Answer 15

-3x+y=-4
3x-3y=6

for this one? the top

Answer 16

-3x+y=-4
3x-3y=6
you want to use substitution for this?

Answer 17

yes

Answer 18

Alright, so give which variable? x or y?

Answer 19

wow my english

Answer 20

y

Answer 21

Alright, so try isolating y on your own, and get back to me when you've done so ^.^

Answer 22

okaaay well im finding x right now
so 3x-3(-3x-4)=6
3x-9x+12=6?
is that right so far I just need to solve it then find y

Answer 23

How did you get -3x-4? Don't skip steps, just go one at a time, that way you'll learn, and eventually with enough practice you can just zoom through :P

Answer 24

So, lets go back to isolating y, how would you do it?

Answer 25

because -3x+y=-4

Answer 26

y = -4 - 3x? Do you see the problem?

Answer 27

I don't remember :( its been awhile

Answer 28

Just take it step by step with me :) and don't rush!