Question

solve each system by substitution.
-6x+y=0
18x-3y=0

Answer 1

y = 6x sub into

18x - 3y = 0
18x - 3(6x) = 0

solve for x then sub x into one of the original equations to solve for y

Answer 2

multiply the first equation by -3 then uses that equatin and add it to the 2nd equation which would eliminate the y's so then you'll have to solve for x the plug it into an original equation and find the value for y

Answer 3

Note: it doesn't matter which equation you rearrange you just need to solve for a variable in one of them and sub it into the other equation.

Answer 4

ok, start off with -6x+y=0
We want to get y by itself so that we don't have to do much work.

-6x+y=0
+6x +6x

Add 6x to both sides. What does it look like now?

Answer 5

what you are doing in these problems is seeing where the two graphs intersect

Answer 6

just a side note on the theory behind this

Answer 7

y=6x

Answer 8

I got y = 6x by rearranging:

-6x+y=0

Answer 9

ok, now we know what y is. So we just fit it into the second equation.
18x-3y=0

18x-3(6x)=0

Distribute, -3*6x= ?

Answer 10

18x

Answer 11

don't forget the negative sign, that will be dangerous.
18x-18x=0

Answer 12

18x-18x=0

Answer 13

0 = 0

Answer 14

add 18?

Answer 15

no, they are like terms so you subtract them

Answer 16

but you can have a 0x, which is just x
so x=0

Answer 17

Do you need help with another like this one?

Answer 18

no x doesn't equal zero

Answer 19

both equations are identical

Answer 20

18x = 18x

x can be anything and they will be equal

Answer 21

18x-3y=0
18x = 3y
18x/3 = y
6x = y

Answer 22

6x = 6x

Answer 23

the lines intersect at all points

Answer 24

x does equal zero, because if you fit 0 into 6x=y you get 6(0)=y
so 0= y

Now fit it into one of the original equations: -6x+y=0
-6(0) + (0) =0

Answer 25

the solution would be ,

\[(-\infty,\infty)\]

Answer 26

x=0 is infinite.

Answer 27

for both variables

Answer 28

austra, we are both right.

Answer 29

x = 0 is not infinite, x = 0 would give us the point (0,0) which is only one of the points of the solution.

Just say that both equations are identical thus they intersect at all times

Answer 30

intersect is probably not the right word to use probably overlap would be better

Answer 31

If you fit it into any of the equations it will work.

Answer 32

why would you add the 18x to the other side? They're like terms, you always put like terms together.

Answer 33

@cocoa020
I dont think you understand that both equations are identical, I put them on opposite sides to show that both equations are equal

Answer 34

and what does your avatar tag lead to? Is it legit?

Answer 35

x = x

Answer 36

alright, ok, I'm wrong. I'll learn from it.

Answer 37

im not trying to rub it in cocoa020 :S

Answer 38

just wanted you to understand this is a tricky question

Answer 39

I'm not saying you are, lol, I wish I could talk to you, because I'm trying to convey my earnest voice into text. It's coming out sarcastic.

Answer 40

well sorry for making that assumption

Answer 41

No, it was a pretty good assumption considering the situation.

Answer 42

I like this problem it is one of those problems where it forces you to understand what you are doing with system of equations

Answer 43

right, and I much prefer equations and formulas to angles and bisectors.