Question

Solve each system of equations by using substitution: Show work and steps on how you got it.

18. 2x + 4y = 6
7x = 4 + 3y

Answer 1

Hello :)

Answer 2

Hello?

Answer 3

so the best way to solve this, is to set the equation to Ax+By = C

Answer 4

the first one is already there so the second one you want to put the y with the x on the left side of the equation

Answer 5

follow?

Answer 6

Woops, are you thinking of elimination Calle? Cause the directions told him to use substitution :D

Answer 7

Oh, good catchzep

Answer 8

ok for substitution you want to get one of the equations to say x= By + C or y = Ax + C

Answer 9

the first one is quite easy if you just solve for x by subtracting 4y and dividing by 2

Answer 10

2x+4y=6
2x=-4y+6
x=-2y+3

Answer 11

got that part?

Answer 12

you there?

Answer 13

yea, just letting you know this isn't standard form

Answer 14

ok

Answer 15

so plug x into the 2nd equation where x is

Answer 16

got that part @Calle87

Answer 17

Fire what is your problem?

Answer 18

substituting and stuff

Answer 19

Substitution is basically like taking the definition of one variable and plugging it into an equation.
If x = y + 4
and x + y = 9
If x = y + 4, cant you just replace that with the x in the second equation?

Answer 20

I am substituting x = -2y + 3 into the second equation and I am trying to get y by itself

Answer 21

Why x = -2y + 3?

Answer 22

Ah, I see. You solved the first one.. Ok

Answer 23

cause that's my answer to the first equation

Answer 24

So whats the problem? dont you get just y??

Answer 25

this is substitution

Answer 26

Yes and....

Answer 27

You are substituting x = -2y + 3 into the second equation

Answer 28

yes I am wondering if it = y = \[\frac{ 17 }{ 11 }\]

Answer 29

7x = 4 + 3y
7(-2y + 3) = 4 + 3y
-14y + 21 = 4 + 3y
Check your work.

Answer 30

yea that's right then combine like terms -11y + 21 = 4, then subtract 21 from both sides ---> -11y = -17 <--- y = 17/11

Answer 31

Nope wait..
-14y + 21 = 4 + 3y
-3y - 3y
------------------
-17y + 21 = 4
See your error?

Answer 32

no we combine our like terms

Answer 33

Yes but the 3y is on the other side of the equal sign, so you must subtract it from both sides.

Answer 34

so y = 1

Answer 35

Yep!

Answer 36

OKAY!

Answer 37

:) If I helped you, would you mind giving me a medal? Thanks!

Answer 38

Well until I get (x,y)

Answer 39

Ok, do you understand how to get x?

Answer 40

yes! I plug y into first equation. Would I subtract 2x or add 4x first

Answer 41

Where would you get 4x?

Answer 42

multiplying -4 (1)

Answer 43

1 is from y =1

Answer 44

Ok so it is..
2x + 4(1) = 6
2x + 4 = 6
- 4 - 4
--------------

Answer 45

I thought it was 2x = 4x + 6

Answer 46

I could see where you got that... This is a time where you got to be careful of silly mistakes ;)

Answer 47

oh okay

Answer 48

If you need any more help, just ask

Answer 49

the point is (5,1)

Answer 50

No it cant be. Try plugging it into the equations, and they wont be equal.

Answer 51

you know how you get a point. For example (3,-2)

Answer 52

Through the process we just did?
You mean graphing it?

Answer 53

no not graphing it

Answer 54

then doing what to it?

Answer 55

you know how figuring out what x and y =

Answer 56

of one or both equations

Answer 57

Oh yes
Didnt we just do that through Substitution?

Answer 58

yea